You do realize that it's the console that determines the speed right?
A very few games have random checks during gameplay on the SNES (such as SSFII). Apart from that, nothing a little switch can't solve.
AFAIK, for Europeans/Australians, only the first Playstation can't run games (PAL) at 60Hz, as in this case, the games are region coded by software instead of the console. In that case, that would be something to worry.
All other consoles (Dreamcast onwards) gives you the choice on which speed you want to run the games.
This whole 50Hz is a thing of the past...
We were lucky enough we had this (fixable) issue instead of having to mod consumer CRT's to get RGB instead of Composhit, Svid or RF!