Well.....I have built BOTH 6.5s in Creedmore and 260 Remington. From a shooting standpoint, its a wash. I do reload both, and compete in LR precision bolt regularly with both rounds. Typically, I will "retire" my bolt brass, full size them, load them differently, and then feed my gassers with the older brass as these rifles are hard on the brass. (Different loads are required for the Gassers vs the bolt guns of course)
Recently, the price for Hornady 6.5 ELD-M rounds has fallen to as low as $1.20 a round, and Prime ammo is also available in bulk for a bit more. At these prices, it is just not worth the time and effort to feed the Gas guns by doing hand loads. Moreover, the brass can be reused from the factor ammo as well.
So - given current pricing, I would opt for a 6.5 Creedmore. I can still reload, but have the option to shoot quality factory ammo as well.
Note - be certain to purchase a high quality "adjustable" gas block, as you will end up spending some time getting it to cycle properly with the HP loads.
Enjoy - you will have the best grouping ARs around.