I also would take the 9.3. I have seen a Brown Bear's clock cleaned with an '06, but like former readers said, the 9.3 is rimmed and more powerful. Regarding recoil, an easy fix for a "light" made rifle is too add weight in the butt with some lead. Sometimes if the gun is scoped, it actually balances the rifle.
The 20 or 28 barrels would be a nice touch and as the old saying goes, "beware of the man who only uses one gun!"
John