dlau, since this is a HUNTING rifle, how much weight would you feel comfortable carrying around in the bush? Personally, lighter the better.
As to how much weight is best for offhand shooting, it depends on what you feel comfortable with. There are no right answers as we are built differently with varying amounts of strength/endurance. Very barrel heavy rifles are not good.
The key is stock fit. If you can shoulder and see through the scope without alot of wiggling and scruching, that is more important then the stability of some extra weight you will never use. How long do you intend to be aiming at the game anyways?
I use to compete in silhouette shooting. The extra weight and balance is fine when you taking slow deliberate shots at known targets that tend not to want and run away.
When I am hunting, fatigue is the one thing I don't want when THE moment arrives. Carrying a big heavy rifle ensures my coordination and reflexes are fatigued especially at the end of a long day hiking about. Having the lightest rifle possible reduces that and increases my ability to make a better offhand shot.
If this is a static hunting rifle, then go with whatever as the rare offhand shot will just have to be accomodated at that time. If this is a comp rifle, the rules you shoot under will limit what you can do anyways.
Jerry