I don't think you're ever going to be able to keep up with skiiers, even with rear entry. They're still going to be faster off the lift than even a rear entry binding will let you. They're going to have to wait a few seconds for you anyway, and if they can wait 3 seconds, can they not wait 10 or 12? I can skate off the lift to the start of the trail and buckle in pretty quickly without rear entry.
I don't think rear entry in and of itself is appealing but the way Flow's uni-strap design distributes pressure differently from the two strap design might make it a good choice depending on your foot/ankle shape and your boots. The best bet would be to get your boots all laced up and strap in and see how these feel on your feet.
Also, consider looking for 2011 bindings. You can probably snag $200+ price point clamps for under $150. I know Targas were going for $160 at the end of last season.