I've got one, and I like it a lot. It's not going to shoot like a "traditional" balanced spool valve gun, but it's still fun to shoot. I should mention though that if you buy a REV-i new, it won't come with a gauge backcap, but a regular solid backcap.
I have an NT11 and i love it i know that's an unbalanced spool valve gun, i just was wondering why haven't i seen more of them, granted i just discovered them but i was out of paintball when they first came out and to be honest i havent heard anything good about DP guns. i can't even find on on ebay unless its new. thanks though i will look into them more.