Should I fix 40D shutter and use as a backup?

Right now, I have a 40D and an XTi. I do the occasional wedding, and some family shoots (as well as personal/family stuff). I am planning to sell my XTi for a little extra money and put it toward a 7D, which would become my primary body.

My question is, should I get my 40D shutter replaced when it goes out (which could be anytime - currently has about 90k shots) and use that as my backup? It is in incredible condition for having that many shots on it, and I haven't had any issues with any of the dials or functions; and I just love the camera (how it functions, the ease of access to controls, etc).

I'm just wondering if it makes sense to spend the $300-$350 or whatever it is to get the shutter replaced? Or should I sell it and get what I can out of it before that happens, and try to get a T1i or T2i (that would be my price range for a backup, if I don't fix the 40D) as my backup.

Does anyone have any experience with the 40D after having the shutter replaced?

Thank you