What are the benefits to upgrade from 4.0 to 4.1? Are there games that will not play on 4.0?
No games 'require' any System Menu version and it's unlikely they ever will. Each game requires a certain game IOS, that's all.
There was no major change between 4.0 and 4.1, just a bug fix really and I quote Wiibrew
I'm on 4.0 by the way, everything seems to work.4.1 Fixes a problem related to the Wii MotionPlus video and the SD Card Menu.
Not really doing much Wii stuff these days.