with the 05-07's, One thing you'll notice is the rear sags a bit more and will feel alot softer and slacker than the atomic. If your a smooth rider It might annoy you and you may be better off on a single pivot or somthing with less travel. If your a point A to B rider you'll like it because you can just point and shoot... You have to work a bit harder to jump them and get them to do what you want. Still, top notch bikes, I havn't been happier with mine.
The 08's are extremely nice. They ride a little different. The back feels way more nimble and you can throw them around alot easier. Basically all my dislikes in the 05-07 have been fixed in the 08 model. When I ride the 08 I can really feel a positive difference. (But thats my personal opinion)
In the end it really depends on your style - I'm just generalizing about the smooth/agressive styles for examples sake, theres really too many to pick from and alot of different bikes will suit you. How much you'll get out of a bike also has alot to do with what quality suspension you run and how well its dialled in, be aware of this when you test bikes too...
For the amount of clams you seem to be interested in shelling out on a frame you'll be happy with whatever you end up with, just make sure you havn't made up your mind before you have a ride on a few different bikes. It's easy to be sold on V10's already because they're sexy and seductive at first... but that doesn't necessarily mean you'll have a happy marriage!
Also remember anyone who offers advice (Including me) will be biased. =)