I have two 6.5 Creedmoor's, one 24 inch sporter and one 26 inch heavy barrel. I use a suppressor on both. Factory 140 gr out of the 24 inch is 2700 fps just as Hornady advertises on the box. Velocity from the same box of shells in the 26 inch is 2875 fps. With R26 velocity in the 26 inch is 3035 fps. It depends on what you see as advantages and disadvantages. Both rifles are Savage actions with Criterion barrels. I have a 6.5x284 Cooper Phoenix with a 26 inch 1/9 twist snd it will stabilize a 140 gr at 3000 fps. If you get the 1/9 twist it will not stabilize the 147 and larger. Only you will know which is best for you, but I never notice the extra two inches and the 24 inch rarely gets used, and I have four different stocks for it. In the Savage stock it groups 1.5 inch, in the Boyds it grouos .7 inch, and in the Bell and Carlson Medalist it groups .2 inch. Stocks sure make a difference.
Speaking of barrel length. if you get a chance pick up a 42 inch barrel Kentucky flint lock and hold a sight picture. If the guy asks "hows she hangin" he is asking you a totally different question than you may suspect.
. I find the same is true going from my 16 inch Ruger Ranch in 6.5 Grendel to my custom 300 WM with a 28.25 inch barrel ---- with a suppressor.