Your numbers don't add up...
6.5 Creedmoor
4.49", Hornady 129g SST or IB, .485 B.C. @ 2950fps, 24" barrel
.260 Rem
4.60", Hornady 129g SST or IB, .485 B.C. @ 2950fps, 24" barrel
A bullet with the same BC launched at the same velocity will drop/drift the same...So, the 6.5 CM and .260 Rem will be exactly equal, no advantage to the Creed.