Interesting you bring up the bb drive system. I saw the video where it was suggested Cancellara was cheating with a hidden bb motor. I thought to myself that if I didn't have the Bionx I'd actually prefer a smaller less powerful and much lighter motor in the bb. This would help weight distribution a lot since it's basically in the middle of the bike. Having a big heavy motor at one end of the bike means I can't take corners very fast. It's a real pain.
Some smaller less powerful ebike that had a bb motor and had a really light battery that basically helped me up hills that I could recharge through regenerative braking or setting a recharge mode similar to the Bionx is what I'd prefer. I don't think what I want exists yet, but nice to hear that there's a lot of development on bb drive systems. I think I'd prefer that far more.