Should I keep Guitar Hero III?

[GooseGaws]

Okay, I recently picked up the Rock Band Special Edition for Xbox 360 and I sold the guitar out of the set on eBay, as you cannot use it with the Guitar Hero series.  I then purchased a Guitar Hero III bundle in order to obtain a second guitar in addition to my Guitar Hero II Xplorer, both of which guitars are compatible with Rock Band (and the Les Paul is wireless, of course).

I haven't yet opened the Guitar Hero III game itself, and after playing a large amount of Rock Band this past week, I'm not entirely sure that I want to.  My question is: is it worth keeping Guitar Hero III, or should I try to sell it?  If anyone has played both games extensively, I'm particularly interested in your comments.