The Creedmoor discussion seems to go 3 ways, the indifferent, the Creedmoor defenders and the Creedmoor's no better than this crowd.
Hornady says that they developed the Creedmoor so they would have set the chamber and cartridge specifications and therefore could create ammunition at a higher quality level and then they admitted that they wanted to market it, (make money) their answer.
Here's my performance observations as a purchaser of a rifle based on one of the new fangled Hornady cartridges.
As of late yesterday I finished my compairison tests of my Aero Precision AR15 M4E.
The tests were CQB ranges, 16, 25, 50, 100, 200 300 yards. Also steel plates from 300 to 650 on torso sized plates. Rifles tested M1 Carbine, Stag Arms S1 M4 Clone, Colt H-Bar AR15 A2 in 5.56 NATO and my Aero Precision M4E1 in 6MM ARC. This was shoot and scoot field shooting, 100 yards + prone shooting no bi-pods.
All the stats are too much to waste your time on so I'll give a general expectation and end result evaluation.
My experiance when I was much younger was with an M2 Carbine in M1A1 configuration as my secondaryweapon, in close, a devastating CQB system, out past 200 yards not so much. I have not been extremely happy with any development since then but I thought the 6 ARC was worth a look.
In close the Aero in 6 ARC was the best by a very little, the 30 Carbine and the Stag M4 Clone were very close, the A2 H-Bar a bit slower, the accuracy of all 4 were devastating.
At 100 the 6ARC and the A2 were the best, near identical accuracy . The Stag accuracy and the 30 Carbine were close. At 200 the results were similar to 100 yards.
At 300 the 30 Carbine fell off a cliff, the 6 ARC and the A2 did well and the Stag was next to last, better than the Carbine by quite a bit but nothing like the 6 ARC or the A2.
At 400 the Stag was like the 30 Carbine at 300 and only the A2 and the 6 ARC were used at 500 + Yards. The A2 dropped way off at 500 with XM 855 ammo but picked up and did well with 68 grain match loads, the 6 ARC was much better, same for 650 except an increased improvement by the 6 ARC over the A2. I got what I bought and I'm happy even though it's a modest improvement.
Moral of this winding, wind blown story, evaluate before you buy, stop being overly negative about a companies motives about development and stop being overly zealous about new developments. Just evaluate honestly. Well that's what I tell my boy.