Now here is the real draw back, and one that is not discussed in the Gun Rags. The barrel life with the 6.5 Creedmoore is a scant 4,000 rounds. Sounds like a lot of barrel life to the once a year hunter but to the target shooter as you are talking about less than a 2 year barrel life. The .308 will go at least 6,000 and if given good care can go as long as 8,000 rounds
I don't have a 6.5 Creedmore, heck I own .223, 308 and 30-06 match rifles.
However I have buds who do regularly shoot 6mm and 6.5 mm rifles in Highpower and Long range competition.
The typical "accuracy' life of a 6.5 mm is around 1500 rounds, I think the 6mm cartridge adds a couple hundred rounds on that.
A 308 barrel is good for 5000 rounds.
Barrels are not all the same, a barrel made from an exceptionally soft lot of steel will shoot out faster than one that is harder. So barrels will have a plus or minus factor.
You can still shoot perfect scores at 300 yards with barrels that won't group worth a darn at 600 yards.