Flushable kitty litter...should I flush it or is it bad for my plumbing?
Very interesting question and it is all in the wording.  Flushable meaning can it be flushed?  Yes.

Does it break down like human waste?  I doubt it.  So yes you can flush it.  Will it cause plumbing issues?  Maybe.  It really depends on the size of the litter and how long it take for it to break down.  

Real-world experience...  My plumbing contractor has had more than a couple jobs because of litter clogging pipes, especially iron pipes.  

This question is kind of like asking should you flush kleenex or baby wipes - you can but they can cause issues.  The only thing that should go in your toilet is human waste and toilet paper.  These things break down easily.