Please search on the net yourself.
BTW, Wireless flash was in the flash back in 1990's with wireless slave. If you don't know what i-TTL/CLS can do, find out. I've told someone the same thing 3x for over a year. Yet, nothing has changed. The holding down button IMO is much better; nothing to stick out like a sore thumb.
Do a little research instead of just listening to what people say. A good place would be
here.
As for DX, well you have no idea what you are talking about.

Clue: Sigma 12-24 is not DX.