Never rebuilt, 89k. They give me no trouble whatsoever, I have no oil in any of my intercooler pipes.
Like Sean Johnson said, I would worry about other things besides the turbos. You are MUCH more likely to have your transmission go out, or the transfer case, or spin a rod bearing. With any of these you're talking about several thousand dollars to repair. If you have problems with your turbos, you can have them rebuilt for $275 apiece. Hell, you could wind up paying $275 apiece on tires, just to put it in perspective.