I have asked this question and done many a Google search on this exact subject! All I have found was he said she said and no real evidence. No TSB's, no recalls, nothing more than I heard from my best friend's, uncle's, brother's, barber's, butcher's, inlaw's, next door neighbor's, grandson's, dog sitter that someone had an issue with the v6 drive shaft. And from there it became FACT
I have also had mine over 120 mph and not even a weird shake, was as smooth as if I was going 60 mph
That said, will an aluminum drive shaft be better than stock, most likely.
Well the 2005 mustang is known for having driveshaft failures at 120 but if it's 2006 or up don't worry about it. A good company for aluminum driveshafts are shaftmasters. Get a 3.5" one if you're lowered and a 4" not. I have a 3.5" and it gives me smoother acceleration and better mpg.