550 out of the box is a bit stronger than the 261. The 441 is like packing a Volkswagen. And well the 880 when speed matters isn't setting any world records
It'd be cool to see Stihl take the top of the mountain. Especially with new technology. The 661cm is looking great so far. But there will be a point when the 372 is replaced and I think by that happens more companies will be trying this technology. Performance won't be the difference so much as weight and handling. It might be a while before we see another AT or M-Tronic saw release so I'm curious to see how things shake out here.
I've not ran a 550 but I really like a 261 for a baby saw. The 461 is the best 70cc saw right now. I wish husky would make the rear handles more round on their saws. That alone is almost enough for me not to run them anymore. That makes my hands hurt more than the rubber av stihls use. I wish I had time to go see randy and see how the 661 runs myself.