I switched from Force's to SF45's, and the highback flex is not all that different. The SF45's do feel a little stiffer, but I also feel a lot more locked in with the SF45's due to the fact that I can get the straps tighter more comfortably due to the extra padding when compared to the Force. IMO the 2 bindings aren't very different when it comes to response, and while the SF45 highback definitely feels stiffer when you flex it by hand, the feel when strapped in isn't too stiff by any means. I ride it all, from kickers in the park to steep tree lines, and I would definitely recommend the SF45's, the toe strap is PLUSH unlike on the Force, and so far, the durability has been great. I can answer any specific questions if you want to PM me...
Thanks! I ended up getting some SF45s this weekend and got to ride yesterday with them. Tons of adjustments, and to me they were the perfect stiffness. Just a bit more responsive than my Inverters(Force/Data mix). I really like them a lot and after messing with the adjustments though out the day, really have them dialed in and find them to be extremely comfortable with a secure feeling. My Unions are great too, but the Flux I just got are a step up. Thanks for all the feed back guys.
As for DMCC Vs SF45, now I actually have some experience with both and unless your doing big mountain lines, Jeremy Jones, or Xaiver style, the SF45 will work for everything, probably those big lines too. The DMCCs high back is pretty stiff, if I were to rate the two on a stiff scale 10 being the stiffest. I would say 7 on the SF and 9 on the DMCC.