I have used both the 277 cutting edge and the 300 Berger OTM. I have had better results past 2200 yards with the 300 Berger. Both shot very good under 2200. My personal best long shot with the 300 Berger is 2616 yards at and ELR match. Rumor has it Berger is going to offer a 320 something grain OTM I plan on talking to them at Shot Show.
For what its worth I have shot all the bullets above but the 265 ABLR. I also shot the 300 grain Lapua Scenar. The 2 most accurate bullets past 2200 yards in my AI-PSR were the 300 Berger and the 300 Scenar with the Berger having a better BC and being affected less by the wind then the Lapua. I guess it could come down to which bullets works best in you rifle.
I used the Nosler Custom Comps 300 grain for barrel break in as they were cheap and ended up shooting petty good also.