I've read about it a shedload, and I'm fascinated as to why someone would do it for a 4% larger tire. Yet we have a whole industry and consumers doing exactly that.

Anyway, I like to run wide 26" tires, 2.25" to 2.35". On a conversion, you'll have to run narrower 650B/27.5 tires. That alone is a dealbreaker for me. But, yes, a 2.0" 650B tire should clear many 26" bikes except for XC race bikes that can't even fit a wide 26" tire.