Truth be told, I just got the TT30 and haven't ridden them yet. I did ride the Feedbacks plenty, which are very very similar to this year's SF45, but a couple small differences. That said, by feel, the 2 bindings have a similar highback flex. The SF45's are a little taller, about 1cm, so not as high as your Cartel skybacks (then again nothing else out there is). The main difference is that the SF45 base is a bit stiffer than the TT30, but I can't comment on that difference yet. I think the SF45 will be a much better replacement for your Cartels. That or the DS45.
Thank you for all the help guys. I didnt really want to spend a fortune on bindings thats why i was looking into the tt30's but im going to def look into purchasing the sf45