I think you have to choose: max performance and more barrel life, or more barrel life and lower velocities.
The 6,5x55 will beat the 260 and 6,5x47. The european reloading manuals are conservative with the 6,5,x 55 loads because many military mauser actions were converted to sporter rifles .
I have shot 140 bergers in my 6,5-284 at 3100 ft/s in a 26 "barrel with no sign of pressure... you wont reach that in the others. But of course barrel life wont be (for max accuracy) much over 1300 rds.