Re: varmint rifle????
If you are going to throw mule into the equation too, Kirby recently posted some info on the 6.5x06 AI. What he wrote made a lot of sense. It is a very well behaived cartridge and has very nice down range qualities.
If you are set on a short action rifle, go with the 6.5x284. It has a legendary reputation amongst the Benchrest crowd.
One next question, are you willing to reload your own ammo for this build? If not - go with a 25-06.
Snohomish Co. Washington
NRA Life Member