Scotty likes the SF45 because the binding gives great response. Especially when he is doing his one footed trickery. The high back on this model, as well as the DS30 and DMCC light can be swapped with each other too switch up the ride. OUt of the box it comes with the higher end towards the inside of the bindings. Scotty does this, because it gives you the most response. When you switch the highbacks with each other you put the higher end of the highback towards the outside, giving you more material to push up against on the outsides of the bindings for tweaking out tricks.
Ian Sams and Erik Leon both do this with their bindings.
The DS30 and DMCC light both have the same highback made of super tough nylon. It is going to feel softer than the SF45 because of the shape of it.
Ian Sams rides the DS30 because he likes a softer baseplate for jibbing. The baseplate on the DS30 is made out of a 30% fiberglass mix.
Erik Leon rides the DMCC light because he likes a little more response from his baseplate when he's flyin fast through the park. The DMCC light's baseplate is made from a carbon infused fiberglass... making it lighter, and more responsive than the 30% blend of the DS30.
Scotty Vine rides the SF45 because he likes response in his highback and baseplate. The SF45 uses a 45% blend of fiberglass in the baseplate, making it the stiffest and most responsive in the Flux line up. However, the response in this binding is a lot of fun in the park too.
Hopefully this helps you out to learn the cryptic code that is Flux Bindings...