I have extensive experience with the PVC it's what I'm using now. The problem is that extended periods of heat from the engine causes it to warp some what. As for literally melting, only if you are dumb enough to strap it onto a piece of the exhaust manifold, you have to be sure to route it away from the exhaust manifold as you do with EVERYTHING you put under your hood unless it can withstand well over 400 degrees F, not too many materials can do that. Also be sure to route it away from the coolant lines as they get hot and will make it warp faster and with an imprint of a coolant line. Because it will warp you have to keep checking it which is a pain in the ass as if the piping warps enough the tube can droop, and droop right onto the exhaust manifold. In fact that's exactly what happened to my first pipe, for this reason I have a chunk of rubber (Cut from the stock intake hose) in between the PVC tube and the coolant lines & Exhaust manifold.
It does make for a better shield against heat for the air on the inside of the tube however, and it also makes for a good smooth direct flow from your source of air to the TB, even more so as it warps it will warp towards the shape of the TB. There are HIGH HEAT PVC manufacturers but I have a feeling getting them to make our custom tube would be VERY expensive and possibly not worth the while expecially if contemplating a completely new kind of intake supercharger or turbocharger.