The SF45s are noticably more stiff and responsive. The TT30s are middle of the road flex. I've ridden both and prefer the TT30 due to my style of riding.
I prefer the ankle strap on the SF45 however. Road the DS30 yesterday and can't say enough about the cush ankle strap.
Thanks for the reply, so what is your riding style? Ive only boarded about 7 times before so im probably at an intermediate, not really doing jumps yet or any park...will the TT30 be stiff enough for me? I heard the DS30 is more of a park binding due to flex? and SF45 more an experienced binding as its super stiff...any thoughts?