Just the other day I found my guitars lying around the house and decided to give it a try, so I'm not an expert at this game whatsoever. I play the plastic guitar on medium. I just play for fun as well, so don't strike me dead if I miss a note or two. Just reply back whenever you're online.
Not sure if you're still looking or whatever, but I'm totally game.
Honestly, I prefer the PS3 version now, but I still own all the Wii versions along with my Logitech guitar controller. And I play on Medium too. Until I sprout an extra finger.