I do not race and consider myself a strong intermediate but as others have mentioned, and from what I've heard racers tend to cycle through bindings/F2's and replace before breakage (as with many pieces of sports equipment). So running F2's at a level where you are competing on a regular basis, you'd likely want to have a spare set or two, or at least parts available (which I typically do regardless). Any racers chime in?
I had been riding TD3's (standards then switched to step-ins) for a while until I switched to F2 Race Ti last year as more of an experiment to see the difference in flex (board and boots stayed the same). F2's definitely have more "flex" . I did find the flex characteristics a little more unpredictable/variable compared to TD's and I found it took a couple times out to get used to them. They still didn't feel as solid as the TD's but we are really comparing apples and oranges here. If you are a lighter rider (as in weight) you might not notice this as much. I also noticed the range of motion for when you are driving the knees was noticeable greater in that there was generally more freedom of movement. This was good in some cases but felt a lag time in transitions if that makes sense. Not necessarily a bad thing, just different and had to account for it while riding.
Because of the plastic on them, I had been a little more concerned (having broken Burton raceplate toe bails) and didn't have the same confidence but they held up fine. I did get them dialed in and liked them in the end but forgot what I was missing.
Onto this year. I did a couple days out on the F2's and then decided to put back on my TD3's. All I can say is WOW. Big difference for me...in a positive way. The interface is stiffer, but the E pads take the edge off. Turn initiation was much more responsive and overall felt a better control in transitions and setting the turn. Of course there are a lot of factors at play including riding style, technique, terrain but thought I'd share my experience as a rec rider. I also have never found the TD3 step-ins stiff, or rather never found that the stiffness was a limiting factor compared to the standard bail. The weight of TD's is a little noticeable compared to F2 but doesn't outweigh the performance characteristics of the binding for me.
Don't know if this helps but there you go!