When I bought my PSL a few years back, I had to decide between .308 and x54. I read a few reviews on the .308 and decided against it. Main problem was the mags. They were plastic, and reportedly crap quality. They required a modification to make the bolt carrier not shatter them. Replacements were around $45 when you could get them, god knows what they are now.
I don't have any experience with VEPRs, all I can do is give you advice on the ammo. A lot more types of ammo from surplus to match grade are available in .308. If you handload, this doesn't matter because you can load whatever you want in whatever caliber. x54 does have a little bit more punch, and it's a hell of a lot cheaper to shoot than .308.
Edited by shaneman153a, 06 December 2009 - 01:44 AM.