Back to the topic at hand. In addition to a potential range (per Wh) advantage to the BMC, the BMC has additional intangible advantages. BMC feels that bike handling is superior with the battery moved from the downtube to the seat-tube. I can't certify that, but I'm looking forward to riding it and seeing how I feel about that.
The 10mm of rear travel thanks to the elastomer "shock" in the rear triangle of the frame is interesting and could be a big ride quality boost.
Finally, what range of tires fit these other bikes? One of the things that held me off from getting the iGo was that it was limited to an "endurance road" tire width, whereas the BMC can go up to somewhere in the neighbourhood of 40-42c which is close to an "all-road" tire width.
So slightly more tire volume, the 10mm of rear dampening, and the battery place may all add up to superior ride quality for the BMC. In theory anyways. Pair that up with the ability to tune each of the levels (how low/high each level of assist is), and the the smoothness and long range of high-end STePS, and I don't see any of the others meeting my needs quite as well as this one.
Sure I wish it came in a class 3 variant. I actually wish it was class 3 with the ability to set it lower than 45 km/h on demand (a switch between class 1 and class 3 would do, but the ability to choose where your cut-out is up to a maximum would be best of all), but I understand why they don't do that.