3 years ago i had a custom rifle built.
i too was on the fence between the 2 calibers.
i chose the 280ai for several reasons.
1st was no matter what you have to make 6.5-06 cases. 280ai cases and ammo are available, and most important, if you were to travel and your ammo didn't make it, one could shoot regular factory loaded 280 ammo and still enjoy your trip.
the bc's are the same but different depending on which bullet type and weight you choose.
but, at normal shooting ranges, does it really make that big off a difference ?
nope, maybe, maybe, an inch or 2 at the very most ?
we all shake more than that when we get excited.
it is in a laminated stock at present and will be my main hunting stock. i am having an english walnut stock made for it as i type.
benchmark barrels did the blueprinting, and made the barrel. they did an excellent job chambering and even made a stoney point oal gauge casing made from a test fired casing for me.
it did kill a cow elk at just shy of 300 yards 2 seasons ago, launching a 140 grain barnes ttsx, at just over 3100 fps.
i also just got done fireforming some nickle plated 280 cases. they turned out perfect.
i also have a 264wm, but still working on loads for it.
so far it seems to like 130 accubonds.