Agree, the heavier the better. My F-Class rifles have 1.25 inch blanks. I prefer to have a shorter bbl than sacrifice much in the taper. Having said that i am in the process of getting a new bbl for my 7MM that will taper from 1.25 (first 7 inches) to 1.0 at the muzzle, I am not sure, but I woudl guess this will not make much of a difference in accuracy, but I will be able to tell after I have shot it.
Finally, for my current rifles I use a barrel block becuase of the heavy bbl. This adds alot of wt, I would love to hear what others who use heavy untapered barrels do to support the bbl.