If you look at the ballistic coefficient for the 6.5mm projectiles available, they are ballistically superior to the .30 caliber projectiles. (disclaimer: I taught physics for a while) The only thing the .30 caliber projectiles have as an advantage, military-wise, is the wide availability of projectiles for special purposes, such as tracer, AP, APIT, etc. There is a reason that 6.5mm rifle shooters have won the National Championships in several categories for quite a while now, but I do agree that most people won't see the difference between it and the .30 caliber cartridges. A "long shot" for a deer hunter here in Mississippi is generally what I'd consider close range, ie, less than 300m.For a general purpose, do all cartridge I still believe that .308 is king, the 6.5 is a paper optimized cartridge and with the small deer that we have here in south Ms proper selection of projectiles is paramount.
Projectiles like the Hornady ELD-X used in their precision hunter cartridges seem to perform ideally vs the fusion/core lokt bonded soft points, especially at closer range where the velocity is higher.
Personally I don’t own a 6.5 because the cartridge isn’t optimized for my uses, and 90% of the people that I see come through the shop don’t benefit from the 6.5 over a .308 or 7mm-08, but because of marketing saying it’s “the best thing since sliced bread” people are buying it up.
Personally there on 2 cartridges that are “new” that I have an interest in for my uses are the 6.8 SPC (short barrel suppressed AR-15 performance for deer and hogs) and 6.8 western (short action, Long range, high energy on target).
I have taken a LOT of game from crows to coyotes to large (relatively speaking, this is Mississippi) deer. Some with Swede milsurp when I wasn't hunting but came upon a deer or coyote as a target of opportunity, but the Swede milsurp FMJ has such a thin jacket they disintegrate on impact with flesh. If you have seen such a projectile strike a coyote, you know what I mean, the jacket basically sheds on impact. I never understood the need for the 6.5 Creedmore when the 6.5 x 55 is considered the "go-to" caliber in Europe for most game, including moose.