Should an issue arise with that pumping system (and it is a possibility) and the oil does not get back to your engine, you will lose your engine and turbo. Now, that can happen with any setup I suppose, but it's more prominent when you have a situation where a scavenge pump is required.

Also, part of the allure of the rear mounted turbo is that you don't necessarily need an IC. The thought is that it has cooling time on it's 15 foot trip back up to the intake.