While I don’t own GHWT, I do own Rock Band 1/2, and always follow the news posts on game sites about both games. I’m pretty confident that the recent iterations of both games are mostly compatible with each other’s equipment, one exception being the expensive ION drum set not working fully in GHWT. Kotaku recently posted this compatibility list unfortunately it seems that list contains errors. I would keep an eye on that page for an update when the proper compatibility chart comes out. On further research, here’s another list of compatibilities, which indicates that with the X360, almost all guitars work with all games except GH2 and 3. Have fun rocking out with your wife! :)