It's maybe just me, but I'm confused about people asking if System Menu 4.0 is working with SoftMii, cIOS, Backup Loader, and other software hacks.
If you're using software backup solutions, then there's a 98% probability that you're using pirated WAD games. The only thing this firmware update does is the option to move a channel to SD card and boot from there (which it doesn't actually do, just a half-assed hackjob), and it's already been confirmed several times that pirated WADs will not work with the new SD card channel.
...so why would you want to update? I can't see the logic in all this stupidity.