Wifi will eat more energy hands down than a dimmed down lcd - but I'd like to know how long exactly you can do lv with a smartphone, did any 6d owner do any benchmarks yet?
I had to delete my earlier post because I tried out what you had suggested (above). Well, the LCD does not dim when shooting nor does it go "off"/blank when shooting with a smartphone (not automatically at least and there is no setting that I notice to make it go off after a certain time lapse) ... I guess it can stay on for as long as the batter is alive or the EOS remote shooting is active on your phone. I've got my 6D connected to my iphone for the past 10 minutes and it shows no sign of timing out.
Well ... the 6D timed out when my iphone locked itself up after the auto-lock at 15 minutes. It "woke up" as soon as I unlocked my phone.
One can conclude therefore that shooting with a smartphone will reduce the battery life even further because both WiFi and LV are being used together.
1DX, 5D3, 600D, RX100
16-35L, 24-70L II, 70-200L II, 100-400L II, 50L, 85L II, 135L, 17TSE, 24TSE, 40, 100 macro, 18-55 II, 55-250 II, 1.4x III, 2x III, 600RT x 4
When it comes to gear, it is better to vote with your wallet. Bitching on online forums like a lunatic doesn't get you anywhere!