I feel your pain, brother.Yes, that was my experience. We would only have freezes when the mike was in use.
I had only just read your note about deleting the save file to fixi the freezes -- I guess I won't try that after all.
Unfortunately, my wife only likes to sing. Whenever we'd play together, we'd end up with a hang every few songs. That killed off her enjoyment of the game. Restarting the game via HBC just annoyed her more (too many selections).
And every time I forgot to set the date back to the current time after playing would cause problems with games the kids used. In particular, Wii Fit would erase their progress if it was ever started with the clock in the past. They eventually refused to ever play with RawkSD -- they'd much rather just play vanilla RB2.
I've tried to get this to work better, but all I keep running into is cynical mocking from one of the devs.
I am just about ready to move on, like everyone else, I guess (in terms of getting a new build).
By the way, about the freezes, you could try switching the mic to the other USB port and see what happens.
I've not tried myself, but who knows.