I drive a 3000GT VR4 so I have some experiance w/ turbo's. So here's my opinion on this subject

Your net power gains wont be at a low enough rpm to help you when you're crawling around a trail below 10 mph........unless your in 4WL. Then in that case your MPH/RPM ratio will be to small to dissipate the heat the turbo is producing, even if you have a intercooler.

Now if you want one for on the highway passing or towing it's a great idea. The power gain would be were you need it and the airflow across an intercooler would be more than enough to keep you detonation free (granted you're consevative with the boost level). And yes a turbo will give you more of a power return than a supercharger.