What advantages specifically are you looking to gain? You already have a .338 Win Mag, and I'm not so sure the 7 will outperform so stunningly on bullet drop unless you really are shooting at or past 500 yards. And even then, that's primarily if you're putting a 140-grain 7-mag against a 225-grain .338; the 160-grain 7 hardly stands apart from the same .338 round. And the 140 doesn't outshine a 180 that much.
You can play around with this ballistics calculator and decide which seems to perform better in terms of drop and energy.
http://gundata.org/ballistic-calculator/
If recoil is the problem, on the other hand, then that's another issue, in which case my vote goes to the 7mm.