Hmmm....Silver....you had me there for a minute! But to mention the "horsepower" calibers such as 338WM, Weatherby/RUM's and then to foul it up with the last sentence. The 7mm RemMag might be popular, and is a nice caliber, but please don't put it in the same paragraph with the others mentioned!
Without getting too off course, I would argue that with the 7mag (Rem not the Weatherby) is only marginally more potent than a .270 or .280, not enough difference to warrant it's popularity other than the word "MAG" is involved!!!

As per the original question....only you can be the judge. The .338 Federal is a milder kicking version of the .338.
The .325WSM is a blend of the .338 and the .300...."tweener". More bullet than a .300 and flatter shooting than .338. I like the caliber. But to each his own.