I think Porsche might want to argue against your quote about "being handled in a gentle manner" with the Al engine block on their GT3. It's been their most successful racing car engine for years and is bulletproof as far as those things go. In no way will the truck engine exceed the strains of a racing engine designed to run at high compression at 5-8.4K for hours on end. As far as strain - the truck has an automatic transmission which is easier on the engine, and puts out less HP and torque perdisplacement, lower compression, etc.
Of course there will be a few problems as there always are with something new, but to blame in on AL will be foolish. Hell, they even have had Al DIESEL engine blocks for a while.