I recently bought an Alesis ControlPad (Awesome!) and it came with EZdrummer LITE.
 
Question… Is it worth investing time with EZdrummer considering I’m happy with and competent using SessionDrummer3? 
 
Just trying to stay focused on making music and not squandering time on software I’m not going to end up using.
 
Thanks to all input

IMHO it is definitely worth trying out EZdrummer.  It is incredibly simple (EZ) to use, and sounds much better.
 
Please try it.  The difference is amazing.
 
Upgrade to the full version is very little, and it comes on sale for less if you shop around.  You then get the full kit, and can add the expansion kits, which are fantastic.

+1 for EZDrummer. Love it!

Time+Space have a special on at the moment to upgrade to the full EZdrummer for £43.49. Well worth it IMO.
 
Apart from giving you the full kit and cymbals, and lots more MIDI loops, it enables you to add on the expansions, which are fantastic.  I have many of them, and they sound amazing.

EZDrummer was on sale last December for $27. I would wait for a better deal. FWIW, BSD Eco (the "EZDrummer" version of BSD) is on sale this month in the $25-$30 range (shop around for best deal). 

I have several acoustic drum libraries but I think it's not exaggerating to say that EZD is the best for songwriters/musicians. BFD Eco is the worst of what I have.

another + here for EZDrummer.
Be patient and the specials come out almost monthly to get either the packages or just the MIDI loops for that drum package.
Very flexible and the sounds are top notch.
 

I have Superior drummer, EZ drummer (reg.and lite) and Session drummer 3. For the price you mention, I personally would just buy one of the session drummer 3 add on kits from the sonar store. I think both Session 3 and EZ Drummer function about the same, so if you are looking to spend the cash then why not just get an extra kit for what you already have (Session3). 90% of the time I start a new song with session drummer and then switch it to Superior Drummer when I'm getting near of raw tracking. With this in mind though, you may want EZ drummer as the additional kits available from toontrack can be used in Superior as well. If you are eventually thinking of buying a top of the line drum synth such as Superior then you can start the journey with EZ drummer and the expansion packs and still be able to use then once you upgrade.

 
 

EZdrummer is quite a big improvement on session drummer though I don't know how it compares to session drummer lite.
 
BFD Eco as scook pointed out is another option that is currently on sale for less than EZdrummer and is in my opinion far better than EZdrummer.
I have both but really you should do your own research by checking out their sites and seeing which you prefer.
 
I'd be interested to know why Jlien X thinks Eco is the worse although if all you want is out of the box premixed and processed sounds EZdrummer is easier but if you want to create your own sounds then you'll find BFD Eco is far more flexible than EZdrummer, has more kits and a much better mixer + a full suit of very useful effects included.
 
Best of competitions aren't always proof but here's one that backs up my claim
The Best Virtual Drums
 
Steve