My 338F experience is nil, but I ass-u-me it's pretty similar to the .358, which I have used quite a bit.
The appeal of something like a 338F is that at moderate ranges it hits hard, kills well, and (I like this part) doesn't turn meat to jelly.
To come back around to the 7-mag, it is simply capable of doing more than a 338F is. Period. But- which one would I rather punch a deer in the shoulder with at 40 yards? The 338F, hands down.
So I could l could, I think, love a 338F for the same reasons I love my .358. But they'd be different reasons than why I'd love a 7-mag.
Just IMHO!