I have been struggling with the same decision of 300WSM or 325WSM. Studied it a while, here's what I know.
As for ballastics @ muzzle and 400 yards: Ballistic Silvertip 180g
300WSM--------------VELOCITY f/sec----------325WSM
MUZZ-------400YDS---------------------MUZZ----------400YDS
3010-------2301-----------------------3060----------2242
300WSM--------------ENERGY ft-lbs- --------325WSM
MUZZ-------400YDS---------------------MUZZ----------400YDS
3621-------2116-----------------------3743----------2009
Really a wash as he mentions. More bullet selection with the 300WSM. Haven't been able to find a gun or shells yet for the 325. Also, 300WSM is also slightly better than the 300Win Mag.
As for the guns, I have been looking at the Browning A-bolt SS Stalker. BOSS feature not available on 325. I spoke with Browing, and BOSS will not be available for 2-3 years. Others on here have discussed BOSS/Magna-port and feel they definently help recoil but the loudness is unbelieveable. I don't want to wear hearing protection while hunting. Can't sight it in with the BOSS then remove it for hunting. So I have concluded I will get a 300WSM and save the $50 and skip the BOSS. Anyone have other thoughts, I'm still willing to listen. Thanks.