At last summers Triple Bypass I met a one armed cyclist. He was having absolutely no trouble descending huge passes, like Squaw and Loveland. Probably reaching speeds in excess of 50mph. To do that, you need to be confident in your brakes.
I glanced at the ride, definitely two rotors. Not only does the splitter work, it works well. It wasn't a 1x either. I think he had it all rigged Di2 on the remaining hand.
It was an adaptive marvel. I wouldn't quit without making it totally what you want.