This is an interesting topic to me because I have used both types of bindings for many years. I went from using traditionals to Flows and then back to traditionals for just this past year. I have to say both have there ups & downs. So for those of you who have no idea what the difference is, it's quite simple. The traditional binding is one that consists usually of 3 straps that crossover your boot and attach to the other side of the binding, thus strapping you in and connecting you to your snowboard. The advantage of this machine is that it provides for the ultimate tightness that is required for aggressive snowboarding. For example, if you were to go down an entire run taking jumps left and right, grinding on rails, or just taking numerous sharp turns, your feet, ankles, and shins would likely hurt more if your bindings were not adjusted to an appropriate level of tightness. Furthermore, if you take a jump and attempt a stunt, such as a 360 (which is one full rotation while in the air), you are more likely to perform and land it better if your bindings are on right. The disadvantage to the traditional binding is that the process of taking it off and on is much more of a hassle than with the Flow binding. And as you know, unlike skiers, us boarders are forced to remove our rear boot from our binding every time we want to get on the chair lift.
The Flow binding, on the hand, works similarly to the traditional binding with the exception that it allows for the binding to be set to a specific fit or level of tightness, and will then open up in the back (where the back of your heel starts to the upper ankle), allowing for your boot to simply slide in or out with the greatest of ease. Now, once this portion of the binding is down and you've slid your boot in, you can then lift this part of the binding up into place and it will lock and secure your boot into place. It is very convenient considering that as snowboarder, we have to remove our rear boot from our binding at the end of every run. The bad side is that although the binding has safely secured your boot to your board, it just isn't able to accomplish the same level of tightness as a traditional binding, which is why the greater majority of professional snowboarders out there do not use Flow bindings. With that said, if you are not trying to win any medals or take crazy jumps, I would definitely recommend the Flow binding. The convenience of slipping your boot on and off surely is significant, and if I didn't love jumping so much I would go back to them in a heart beat!