I fit a DA Retro switchless region free mod to a PAL Mega Drive, with a tri-colour LED and no toggle switches, then see how much 60Hz really changes.
A Fenrir-equipped PAL Sega Saturn gets a switchless multi-region 50/60Hz mod, a snapped PSU board repair and a soapy bath, then a before and after test on real games.
I mod a PAL Atari Jaguar to run at 60Hz by removing the zero ohm link at R140 and adding a 50/60Hz switch, then compare games side by side.