Im in the same boat, and 10lbs is about where i start finding 300s comfortable to shoot.I think a shooter, with higher skills than me, could get more range with a 10 pound 300 Win Mag and 180 gr.
Ill stick with 7Mag (or 7STW), under 10 lbs, if the rifle gets down around 7lbs ready to fire Im much happier with a standard or short .24-28 cal. 5-6Lbs and Ill stick with a short action, which is where i think the 6.5s and 7-08s really shine in terms of performance VS recoil.