Xpansion Tank 2...a good buy?

[Harpo]

I own and use SampleTank 2 XL along with the sounds that came with it. I've been really happy with it over the years. Stumbled across this today:

http://www.ikmultimedia.com/xpansiontank/features/

I still use PT version 6.4 and am happy with it as well. (Not exactly "cutting edge" here ) I'm on a budget (working musician) so this price for this ($49) seems right up my alley. I notice it comes packaged with SampleTank 2.5 XT. Does that still use the sounds I already have? And is this worth buying in general? (Keep in mind I like the SampleTank 2 XL I'm using now) What I'm hoping for is adding additional sounds and maybe even a better version of SampleTank.

I'm also curious about some of the loops and the sync function. I assume you can lock the loops in with the tempo of the song you are working on....but I can't find any information on exactly how that is done.