Just finished reading the thread, here are some facts I would like to interject:
*W. D. "Karamojo" Bell killed hundreds of elephants with a 6.5x54, 6.5 is enough for anything in North America.
*Benefits of a short action are overrated for hunting purposes - 3 ounces... Really?!
*I handload, and pack my own bags. The availability of over-the-counter replacement "Long Range Hunting" ammo is a joke.
*The 06 design offers about a 150-200 fps increase, which is usable.
*The bullets can be seated further out of the case on the 06 if your using Remington type actions, increasing the capacity advantage.
*The ONLY reliable indicator of pressure is velocity, and you cannot know all the variables in the equation. So BE CAREFUL!
*SAAMI puts the max pressure standard on these cases for a few reasons and one is the steel tolerances, so BE CAREFUL!
*Case prep will be easier, maybe significantly, for the 260.
*Reloading dies should be cheaper for the 260 (depending on the brand selected), but not much.
I am thinking you've chosen these two contenders because of some desire to shoot 6.5s, otherwise you'd have asked whether to get a 270 or 30-06, yet if we stay true to the original topic, this isn't even a two horse race. The 6.5-06 is the 260 plus 10 grains of powder, but clearly you also see that the men making points about Shermans, 270s, 280s, AIs, or whatever else have logically valid points, "If you are going go to a wildcat why not this one?" or, "This one shoots the same weight bullet faster from a factory chambering." Listen, I just spent $700 rebarreling a model 700 to 6.5-06 AI and I am man enough to admit that a 270 Win would have been a better choice pratically, but I didn't make that choice with practicality in mind, I wanted sexy and my version of sexy is what I got. Now, you will have to choose what's sexy to you and how much you are willing to pay to be sexy, but don't kid yourself about the nature of your decision, don't argue the merits of your preference for sex appeal as if it were about practicality, don't post rose-colored data to help your case, and don't insult the choice of another guy. We are all men, honestly stand by your choice.