I think the only reason festool have released this is to have a T handle 10.8v drill in its line up like every other manufacturer. I do prefer the T handle for bigger drills, never got on with the C type but I do also love my CXS, it's so small and light that it does not feel front heavy like the other C type drills. Would definitely go for CXS over this, it actually looks quit big for what it is but will reserve final judgement until I get to play with one.
I don't see why the new CXS batteries can't be used in older drill, guessing only difference is the bigger ah rating which will just give a longer run (and charge) time.
Doug