I wanted to know the same thing and am shocked nobody has really tested a few devises for least lag and shuttering.
I bought the Actiontec ScreenBeam Pro and updated its FW.
I'd say the lag is minimal and is not my main issue now.
Random shuttering can be a pain. It can vary from a only few times to a lot. At this point it seems to be trigger by some games more than others.
Afterburner with a touch profile shuttered a lot (35% of the time) not sure if it a resource issue with the touch profile or general interference in my room.
I played dead trigger 2 with native controls shuttered a lot less(10-15% of the time)
I had the device less than 5 ft during my tests.
This site has done some basic latency tests a handful of these miracast devices. It seems the Netgear Push2TV (PTV3000) had the least lag when used in a pc environment.
I think I will go buy the Netgear Push2TV tonight on my way home from work and test it.
Having a game mode on the tv helps a lot with lag. If you stack the lag with the non-game mode picture processing of the tv and the miracast protocol it becomes very noticeable.