When you upgrade  "you get updated versions of all of your existing ADpaks in the new Addictive Drums 2 format for free!" - good news for those of us who have collection.
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Here are the details from the v2 FAQ on XLNaudio website here:
http://www.addictivedrums2.com/
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When will Addictive Drums 2 be available?

Mark your calendars! Addictive Drums 2 will be available May 13, 2014!

What are the key features of Addictive Drums 2? 
Why should I upgrade from the original Addictive Drums?

Addictive Drums 2 has tons of user-requested features as well as a few surprises from the team at XLN Audio! There are too many changes to list here, but the high-level changes can be summarized as follows: 

1) Lots of exciting new sound-shaping features. 
2) Lots of new tools for finding and transforming beats. 
3) Freedom to choose only the content that matters to you. 

We will publish a more detailed list as we get closer to launch.

But wait, I just bought Addictive Drums!

Not to worry! We have a generous grace period for recent buyers: 

If you purchased Addictive Drums on or after March 1st 2014, you will get a FREE upgrade to AD2. 

If you purchased Addictive Drums in January or February of 2014, you will get a 50% discount for the upgrade. 

Information will be automatically mailed to you when Addictive Drums 2 launches so make sure your contact information in your XLN Account is up to date!

How much will it cost?

The upgrade will cost $79.

Will Addictive Drums (v1) be discontinued?

We will no longer sell Addictive Drums (v1) after May 13, 2014. However, we will continue providing support for Addictive Drums v1 for the time being. 

Owners of Addictive Drums v1 can still purchase ADpaks (for version 1) until the end of 2014.

When I get the new version, can I still open older sessions with Addictive Drums (v1) in them?

Of course! Addictive Drums 2 is completely independent from Addictive Drums (v1) and your existing installation will not be affected in any way. In other words, you can open up old projects with Addictive Drums (v1) and work as you always have in the past. You can even have projects that contain both Addictive Drums v1 and v2 in the same session, in case you don't want to change anything in an existing session.

Will I be able to use my ADpaks in Addictive Drums 2?

When you upgrade to Addictive Drums 2, you get updated versions of all of your existing ADpaks in the new Addictive Drums 2 format for free! All of the presets in the "v2" ADpaks have been updated to make good use of the Addictive Drums 2 engine. We hope they will feel fresh and new again and that you'll have fun re-discovering your existing ADpaks.

What are the system requirements?

The system requirements for Addictive Drums 2 are exactly the same as those for Addictive Keys, with one exception: we will no longer support the old RTAS format for Pro Tools (we do support the newer Pro Tools AAX format in both 32 and 64-bit).

Marcus Curtis
The real question is will people who purchased Sonar X3 Professional after March 1st be able to upgrade to addictive drums 2?
 
Depending on the improvements it may be worth the $79.00 upgrade cost. I got most of the midi add on packs.

I sure hope so.......I got X3 in March!!

No screenshots. :-(

It does not say you have to have both versions. It just says you can run both versions if you like.

I heard the new version is 50% more addictive!!!!!!!!

I'm guessing yes, and the business model is to get their foot in the door with DAW users, then make their money with the ADpaks. I was happy with Session Drummer, I was looking at the ChocolateCake drums, then I tried Addictive Drums and they got me. I'm just waiting to see a special on the ADpaks and they will get my money.
 
Although they will continue supporting Addictive Drums 1, I doubt you'd be able to download it after the 13/5 , and as such, if registering is the same as buying (and I can upgrade to AD2 for free as I purchased on the 31/3) effectively after 13/5 you actually get AD2 with X3, which is a nice little bonus for Cake.
 

TheSteven

Marcus Curtis
 
Which may mean that you can't replace The new version with the old one in a project without redoing all the drums within that project. 

It's not likely that they'll alter the MIDI or automation information so if you change from using v1 to v2 you shouldn't lose your drum pattern or have the hihat playing the snare parts, etc..
 
Hopefully v1 patch settings (swapped pieces, altered tunings, etc.) will be compatible in v2 so you can retain any customization that you've bothered to save as a patch. 
I would expect that any patch alterations that are only saved in Sonar will get lost when the plug-in is swapped out, but that's how it always it (as far as I can recall).  
 
 

 
I am not really worried about the midi information for old projects. I can just move that information to the addictive Drum 2 program with no issues. I have some custom percussion kits because I purchased that add on pack. I also have some custom drum kits that I made that I would like to keep instead of starting all over again. That is really my only concern. I hope I will be able to keep them. I think everything may depend on the new features in AD 2.
 

Scoot
I'm guessing yes, and the business model is to get their foot in the door with DAW users, then make their money with the ADpaks. I was happy with Session Drummer, I was looking at the ChocolateCake drums, then I tried Addictive Drums and they got me. I'm just waiting to see a special on the ADpaks and they will get my money.
 
Although they will continue supporting Addictive Drums 1, I doubt you'd be able to download it after the 13/5 , and as such, if registering is the same as buying (and I can upgrade to AD2 for free as I purchased on the 31/3) effectively after 13/5 you actually get AD2 with X3, which is a nice little bonus for Cake.
 

a year from now if a reformat my hard drive will I be able to download and install AD 1? This is why I really don't like the online installer.If I buy A new computer a year from now will I be able to remove AD 1 from this machine and put it on my new machine? or will I need to upgrade to AD 2?
 
It is too late! I am already addicted to Addictive Drums. I am excited about the new version coming out. I am sure they will give a lot of other drum apps a run for their money. I am just wondering about the changes in the software. I will download the free version and test it out before I commit to the 79 dollar upgrade. I am looking forward to seeing the new features in AD 2

As I write this ... my ADPAKs are being downloaded/updated for AD2.  Apparently, XLNAUDIO has released AD2 a day earlier than I expected.  It's a long download due to all ADPAKs, KIT PIECES, along with AD2 required download and installs.  Hopefully, it's as seamless as its purported to be!  Also, the upgrade to AD2 (the one for $99.95) gives you one ADPAK (your choice) at a great discount.  One final note ... there's a brand-new ADPAK called "FAIRFAX VOL. 1" that's available with this release.  From now on, XLNAUDIO has the ADPAKs (for AD2) priced at $89.00.
 
Just FYI for all AD junkies! 

Does anyone know if/when this will be included with subsequent purchases of X3 Producer?

Thanks, G. I plan on buying X3 Producer in the fall, so it should be good by then.

Thanks for the clarification. I would think that by fall, it would be shipping with AD2 embedded just as AD1 is currently.

Thanks to TheSteven. Bundeled, not embedded - crucial distinction that I missed. Thanks also for the excerpt.