I read about this change today on the XLN Audio Facebook page (yes, newsletters seems to be a thing of the past). However, there is one thing that's holding me back from updating. Their latest post says that AD 2.1.0 has some MIDIpak changes: "Everyone gets the new "CORE" AD2 MIDI library for free! It contains a lot of legacy midi from the old Retro ADpak and from AD1. (Replacing [my italics] the AD Legacy, Beats'n'pieces, Bread'n'Butter, Funky Grooves and Motown Beats MIDIpaks)".
 
This sounds a bit daunting to me, especially the part "contains a lot" and "replacing" (as opposed to "contains everything" and/or "adding"). The first three of these MIDIpacks came bundled with Sonar X3 Producer (AD Legacy, Beats'n'pieces and Bread'n'Butter). Does anyone know what actually happens during the AD 2.1.0 update? Does the Core pack simply add additional beats, not already found on the computer, or is there a risk that some of the beats/MIDIpacks already installed will disappear?

Canopus...that is exactly the question I would like to have answered too.

I also have those midi paks...... 
At the moment, I suppose only XLN will know what the changes are to be......have you contacted them on this?
Please post back if you do find out.

Here's how I understand it: AD1 came with several kits and lots of midi beats. When AD2 came out it had a more a la carte approach and did not include the kits and midi that previously came with AD1. You could buy any AD2 Pak and run it without buying the base program.
When I upgraded fro AD1 to AD2 they upgraded all of my add-on AD Paks and midi as well as everything that originally came with AD1.
I think the new plan is much like AD1 in that the original core content from AD1 will be included with the base program. Nothing will be removed. This only affects new customers but hopefully early AD2 adopters will benefit as well.
The Producer Pak that comes bundled with Splat includes your choice of 3 AD Paks, 3 Midi Paks and 3 kit pieces.
I may be totally wrong but that's how I read it.
 
Rocky
 

So I contacted XLN Audio support yesterday with my question above if beats/MIDIpacks might get removed during the AD 2.1.0 update process (as their release statement might be interpreted), but I still haven't heard anything from them. However, I've seen that they have later added the following comment to their Facebook page:
 
"Clarification on the Midi changes: nothing is removed for anyone - we just repackaged a little! If you never had AD1 before, you get a bunch of new beats that previously only upgraders from AD1 got."
 
That sounds kind of reassuring, but I will personally play it safe and wait for the actual response from the XLN Audio support team.

And now I've just got the reply from XLN Audio support. This is what they say:
 
"No need to worry! All the content that you have previously owned will still be there, only some of it may have been repackaged (i.e. now available in separate products instead of part of a bigger product). The "replacing" part of that paragraph is only relevant for customers who had previously seen those products in the webshop but not bought them or owned them in any form."
 
So, if I understand them correctly, MIDIpacks that I have bought separately and/or came as part of a bundle will still be there. Or at least the beats will still be there. Guess it's time to jump in the water.