As it pertains to S&P I think sheer availability of 30 caliber components and 308 brass would make it easier to buy cheap(er) and stack deep. That, and the selection of tough construction hunting bullets in 6.5 is limited in comparison, but not prohibitively so.

If you're loading your own, either one is fair game. As I stated in another thread, I prefer a heavier bullet for hunting, but it sounds like the majority of your use would be target, so I'd think the 6.5 would have an edge.

Pick the one you think is cooler - you'll shoot it more.