its nice for recording to have the software/hardware version that matches... but yeah i'd go 500 as well (you could also go pro...)
I honestly haven't touched POD Farm though since I've gotten it. It has some nice features, but I don't really like the amp modeling. It's nice for it's time, but obviously amp modeling has improved drastically since then, and I'm glad Line 6 realized that and updated their modeling as well. I'd rather not pay for something that I'm not going to use besides the Variax features.
By the way, can the 500 be used as a midi controller to control VSTs? I REALLY need a MIDI expression pedal. I was going to get a FBV but I think a 500 will be more worth it.