Gains all depends on the amount of boost. Boost high enough and you will absolutely need to reinforce the internals. A supercharger does nto necessarily mean you engine will last longer at all, but rather actually puts MORE stress on your engine. Just look at how a supercharger works and what it works onversus what a turbo works on and you will understand.
Although, a supercharger will be a single unit instead of the plethora of pieces involved in a turbocharger. The mroe pieces you have the harder it may be to locate a problem. A single S/C unit is easier to maintain for that specific reason.