Went to a retro game swap in Portland and a guy with a 1989 receipt changed my whole setup
A vendor at the Portland expo pulled out the original Toys R Us receipt for his NES Action Set, $89.99 plus tax from November 1989, and he let me hold it while he explained why he still runs composite cables on a 13 inch CRT. I went home and hooked my Genesis back up to the old tube TV instead of my upscaler, and Sonic 2 finally looks right to me. Anyone else keep a CRT around just for one console?
Keeping a tube TV around is the way to go for these older systems. What worked for me was hitting up thrift stores and estate sales for a decent 20 inch set, usually under 30 bucks, then grabbing a cheap composite switch box so I can run the SNES, N64, and Genesis all at once without unplugging stuff. The big thing is to check the geometry and color before you buy, because a lot of them have worn out tubes or blurry corners.