I own two .325's (Kimber and a BLR) and a .358 (M7), so I mos' def have an opinion on the subject!
They are, as Dennis says, distinctly different rounds. Starting with .325, while the rifle itself might or might not be suited for the tight stuff, the round itself is more like a 300 mag than anything else. It's easily a 600-yard cartridge.
But as you say, it's about the rifles it comes in, and (say) a BLR in .325 is a TON of practical utility, not to mention raw power, in a compact package.
.358, on the other hand, is quite simply the most efficient moderate-range game whacker there is!
While it is 400-yd capable (with 225-gn bullets), it's best thought of as a 250,300- yd cartridge that flat hammers stuff all out of proportion to the recoil, blast, etc. Love it.
I think they make a great pairing, rather than competing with each other, and in fact the last few seasons my .325's and .358 have the majority of carry time and deer and elk kills for me.
Good luck in whatever you decide! I say, get one of each.
