I tested a bunch of the Flow bindings last season. I was quite impressed with the quality and performance of the bindings, however I definitely prefer regular bindings. For me the time savings were absolutely minimal. At times I struggled to get my boot into the binding where it was meant to be, and it was frustrating. Overall the bindings didn't feel as secure as regular bindings and they weren't as comfortable (I'm sure it takes a while to adjust them perfectly to your boots). I understand the appeal of rear entry bindings for some people, but I wouldn't get them. This is just my personal opinion, and I know there are people out there who would recommend them. Flow have top riders on their team, including Olympic bronze medallist, Scotty Lago. You need to weigh up whether you would like to sacrifice a bit of comfort and performance for minimal time savings. They are legit, just not for me...
Also worth checking out SP bindings:
http://www.sp-united.com/ - they are rear entry bindings with regular straps. You can check them out at Time 2 Ride in Jindabyne.