5D2, 5D3, and 6D: Exposure Meter while Changing ISO

Nikon APS-C camera user here. Looking to potentially upgrade to Canon FF. I had a chance to use coworker's 5D Mark II.

I noticed that when changing ISO manually, there is no exposure meter. ISO/EC are both using the same button and in same mode. So the meter at bottom of VF is used for EC. After exiting ISO/EC changing mode, then standard exposure meter shows up. I googled and there are a few threads that discussed this. But I cannot find any discussion on 5D3 or 6D.

5D Mark III has the same button that controls both ISO and EC. Is 5D3 the same as 5D2, in that it doesn't have standard exposure meter while changing ISO?

6D's ISO button only has single mode, not combined with EC. Does 6D show live exposure meter in viewfinder while manually changing ISO?

Thanks for input. Note that I already knew about AutoISO locked to 400 in Manual mode (limitation on 5D2 but fixed on 5D3 and 6D) and no Exposure Compensation in Manual mode.