If you want a bolt catch that actually releases a hefty bolt and not a little snap of a little piece of metal sheet (a la Star/Ares, KA)...you've got to go with a GBB M4.
From the very limited handling I've had...the both the WE v2 and Inokatsu handle about the same. Nothing earth shattering about the external appearances. Both hefty and solid. I liked the finish of the WE better...but that's really a minor thing.
For performance...the Ino was about twice as much fun as the WE. If the WE was at the "this is great compared to an AEG....but not quite like a centerfire rifle" line....the Ino was just past the "F*CK, this thing rocks!" line.
Mags are horribly expensive (est $100 each)! Lot of parts available. All expensive.
Clone GBB M4's coming out...but you'd be reasonable to expect there to be a difference between a $1500 rifle and a $300 copy.
Aside from the cost....I'd really want to see the shot/shot consistency improve in rapid fire semi/full. As with any GBB, power drops off sharply from "cool down" of the mag.
Best thing to do is to try before you buy. Get out to the games...chat it up with the guys.