Was set on a JPC 2.0, but my friend said the side plates don't stay in position well with that system.  Looking at the 2nd gen Banshee instead.  Anybody have any experience with it?

I'd ask your friend what size plates he's using.  I've heard nothing but good things about the JPC 2.0.

Edit:  Sorry, I didn't see "side".  Still worth checking though.

No experience with the 2.0 but I have the original and it's a pretty nice carrier.  Looking at the 2.0 it looks like they upgraded what the original lacked.  It has much better padding on the shoulders and an integral hydration pouch.  The specs look good and overall looks like a nice carrier.  I doubt you would be unhappy with it.  If the plate bags are similar to the original than you wouldn't have any issue fitting the RMA plates you were looking at.

ETA:  As for the JPC not working well with side plates. I would find out what your friend was using for pouches, his setup.  @daemon734 would be a good person to ask about side plates with the JPC as he uses them. At least he did in the last pic he showed me of his setup.

Awesome, thanks again man.

Ive used it with sideplates, but I use the SKD molle sideplate carriers versus the crye ones.  The crye sideplate carriers are 6x6 only and use snaps, the molle can do both those and 6x8.  The molle carrier takes a little bit of effort to mount but it is rock solid once you do it.