ISO 800 on the 6D has the same DR as ISO 100 on the 60D - a 3-stop advantage for the FF sensor.
Ah, you're comparing a 2012 camera to a 2010 camera. Let me counter this: The 7d has more dr at iso 800 than the 5dc, giving crop a solid 2-stop advantage over the FF sensor :-> ... the dr argument is just a side note, it just happens to add up with the fact that the ff advantage is less than usual for macro.
Swivel screen? Canon's free EOS Remote app allows remote live view from the 6D, and may be more useful than a swivel screen.
Yeah, right, *may* ... but to anyone doing serious macro tripod work it isn't, but I understand you missing out on this because your cameras don't have it so you never really tried. Wifi+Phone requires another gadget and draws power, and unless someone reverse engineers the protocol you cannot use focus peaking nor focus stacking with it. Nice tourist selfie feature mind you or for photo journalism, but certainly not for macro.
As for the working distance advantage, that's the same argument for why APS-C is better when you're focal length limited in telephoto situations. It's only an advantage if you require more than ~8 MP for your output (i.e. you're printing larger than 16x24"/A2) and you're shooting at relatively low ISO. For normal and small prints, web use, or if you have to boost the ISO, the cropped FF image will be as good or better.
I don't think so, first because cropping even the crop shot is usual if limited by the 1:1 mag, so you'll end up with even less mp on ff - I share your opinion for tele photography, but not for macro. Plus as discussed the iso advantage of ff is a bit less than usual because of the effective f-stop and shallower dof (same framing).
For normal and small prints, web use, or if you have to boost the ISO, the cropped FF image will be as good or better.
We have to agree to disagree here unless someone comes up with actual side by side comparisons :-o