EM-5 + Olympus 40-150 4-5.6 620 v 6D + Canon 70-200 f/4 IS 1560 (EM-5 39.74%; 940 lighter)
EM-5 + Panasonic 35-100 f/2.8 790 v 6D + Canon 70-200 f/2.8 IS 2290 (EM-5 34.50%; 1500 lighter)
You should compare the 35-100 f/2.8 to the 70-200 f/4 IS (the latter is even faster) or to the 70-300 non L.
I probably shouldn't have used specific comparison set ups in the way I did - it's hard enough to directly compare set ups even when the sensor size is the same (debates about bokeh, how important different amounts of noise are in the "real world", sharpness, etc, etc), let alone when it's not.
I assume you mean the Canon 70-200 f/2.8 IS is "faster" than the mFT 35-100 f/2.8 in the sense the Canon 6D set up would allow shallower of depth of field. Which is obviously an argument for using one of the comparisons you suggest. On the other hand (and I'm sure you know this already), if shutter time is important (eg shooting action), the Canon 70-200 2.8 should give the same shutter time as the mFT 35-100 2.8 at a given ISO, so in that sense they're comparable. But then other factors come in too, eg if shooting action, you might actually want to preserve
depth of field (to have multiple players, or player plus ball or whatever, in focus) which would mean having to close down the aperture somewhat on the Canon, leading to a longer shutter time. Of course, the Canon set up has lower noise so you could compensate by increasing the ISO and, based on current gen sensors at least, get back to the same shutter time and still be in front on IQ ... although you'd have given up some portion of the Canon's IQ advantage.
Of course, if I'd applied that reasoning consistently, I'd have compared the EM-5 + 12-40 2.8 with 6D + 24-70 2.8, and the EM-5 + Panasonic 24 1.4 with 6D + 50 1.4 ...
Another example problem in my comparisons - it may not be "fair" to compare the Sony 55 1.8 lens against the Canon 50 1.8 II. I'm expecting the Sony 55 1.8 will be a "better" lens, eg sharper, better build quality. No doubt there could be arguments over some of the other comparisons too!
I guess my point was just to give some very rough and ready comparisons of vaguely comparable set ups, and make the point that mFT offers a significant weight saving (and I believe size too) compared with 35mm DSLR so I can see why people are attracted to it despite its limitations/disadvantages, but the situation seems different comparing 35mm mirrorless and 35mm DSLR. The weight savings of 35mm mirrorless aren't as significant (especially as focal length increases), so to the extent 35mm mirrorless has other limitations/disadvantages compared to 35mm DSLR, I'm yet to get all that excited about 35mm mirrorless at least at this point. Time will tell I guess.