Hornady 6.5 Creed ammo has load data right on the side of the box. H4350 with 140gr bullets.....same load you'll end up hand loading, tho the charge and seating depth my differ from your ultimate accuracy load. If it shoots in your gun, go buy a case of that lot number, though I don't see you having a lot of lot to lot inconsistency.
How many 260 rifles in factory form are an 8 twist.....very few. Remington could have fixed that though.
The 260 in SA mag constraints with high BC bullets eats up powder in the casing, seats the boat tail junction below the neck/shoulder junction. The 260 ain't ever gonna change that. The creed case makes a better SA cartridge for long high bc bullets to fit SA mag box constraints.
If you buy a Tikka CTR or Ruger Precision Rifle, mount a good optic, and shoot factory ammo.....if you are capable then you can go shoot and compete in PRS matches. Do the top 10 use it? Why the hell would they? A custom rifle with hand loads would be my choice if money was no object and I was serious about the game.
Buying a turn key rifle, over the counter, with off the shelf ammo, that has the capability of long range.....the creed has no equal, IMO.
Like I said, for a deer rifle, the difference doesn't amount to anything.