I don't think there can be an apples to apples comparison.
The cheapest/lightest Canon FF body (6D) + 70-300/4-5.6L IS costs ($1599 + $1349) = $2948 and weighs (770g + 1050g) = 1830g.
The most expensive/heaviest m43 body w/IBIS (E-M1) + 40-150/2.8 costs ($1299 + $1499) = $2698 and weighs (497g + 880g) = 1377g.
The m43 does have a real cost and weight advantage over the Canon FF system. I personally don't consider the weight difference to be small, but others might.
Another thing to consider is what Dave S brought up. If you need shutter speed, then you would need to boost the ISO on the Canon FF 2 stops higher to achieve the same SS at F5.6 as the Olympus at F2.8. That pretty much eats away the 2 stop DR/ISO advantage of the FF over m43 sensor (and I'm not even sure the Canon sensor has a 2 stop advantage to begin with).
Of course you can use a 120-300/2.8 lens for the Canon and get back the 2 stops, but then the price and weight gap gets much bigger.
You are absolutely right about the weight difference in this comparison. A 6D and a 70-200 f/4 brings them closer on range giving up a little on reach, but there is still some to crop from the 6D on the long end, so the difference is less than what one would think.
Regarding DR as I mentioned in a previous post, the DR is not depending on the sensor size as long as out ouput (like print) with the same DPI. And yes, the Canon is not known for DR, however the pattern noise is much less on the 6D than previous Canons except 1Ds mkIII. The quality of lenses from Canon in the last couple of years has been class leading. On the other hand the resolution from the larger formats are benefiting from the larger sensors. The same advantage you have going to full frame 645 format with a Phase One digital back. The DR is not better but the resolution definitely is. If you don't need the resolution, high ISO and autofucus performance of the best DSRL's, then benefit from the smaller form factor of the m4/3! Simple as that.
Here is what Dpreview wrote on the conlusions on the review of the E-M1: The E-M1 provides the excellent image quality that you'd expect from a camera of its semi-pro level. Its Four Thirds sensor is smaller than the APS-C imagers of its Nikon D7100 and Canon EOS 70D peers, but we think the difference it makes in real world shooting is hard to spot. You need to put the E-M1 up against a full frame camera to really see a significant difference in image quality. And thankfully, the image shake issue that has plagued some Olympus cameras does not appear to be a problem in the E-M1 as compared to the E-P5.
But still: my main point of view on the review on LuLa, especially on the recent ones on smaller formats is the lack of proper comparison with pros and cons relative to larger formats and apples to apples comparison.
Statements like:
Remarkably light and compact with high end DSLR performance. and
I am left to wonder what Nikon and Canon are doing as the mirrorless revolution seems to be leaving them in the wake. Maybe, they will surprise us all. I find not only misleading but also not substantiated. Has LuLa been commenting or reviewing on Canon or Nikon products lately? No! Especially Canon has not been commented on other than in condecensing ways and in fact Canon has brought a number of great improvements to the market.
