i just think for the $ there are much better bindings out there. I too was excitted to try union bindigns cause of the hype, but i feel they are over hyped. go with some k2 formulas, rome targas, raiden phantoms, or some ride bindings, maybe even flux.
I personally don't like the k2 auto or cinch bindings cause they are like bricks and have too many moving parts imo. keep your bindings as simple as possible and take the extra 6 seconds to actually strap in. If you do want to go the fast entry route go with Flows for sure, maybe some NxT-ATs or NXT FSs.
For some people unions work well for them, and for some people it is a nightmare, i think it has a lot to do with what boot you have and what boot size you are. For me the 10.5 DC boots im in were pretty much too small for the L/xl union contacts and i couldn't really get it to work. The burton boots i originally had when i bought the unions it worked better on, but i still had problems with the heelcup and ankle straps coming loose.