IE A pilot who goes off and does 5 hrs aerobatic training in an aerobatic certificate aircraft with a properly rated instructor will be a more capable pilot than if he never did such training?
Of course, everything else being equal, 5hrs instruction makes us all better pilots. But everything else isn't equal. For most people 5hrs aeros instruction would be a trade-off against 5hrs of other instruction. On the whole, I think aeros instruction is not terribly relevant to most GA pilots, especially those whose flying is more A-B transport in higher performance aircraft. I am more a nerdy/technical pilot than a stick-n-rudder man, I will admit. I know nothing about aeros. But, if I am going to get into trouble, it's going to be mishandling an engine failure or messing up in IMC, so I'd rather keep doing 5hrs of sim training on asymmetric and instrument work than bother with aeros. Similarly, I don't read many Cirrus accident reports where aeros training would have had any relevance.
On the PC12 tragedy, we haven't seen a report yet, but I doubt 5hrs in a Bulldog or some light aerobatic single would have made the slightest difference. Scott Crossfield was tragically killed in his light single in a thunderstorm, and I imagine he had more extreme aeros and performance experience in a lifetime of flight testing and flying rocket ships than most pilots out there....