tried and true is a good way to look at it. i was thinking of finally building one of these large .30s due to the new 225gr Hornady match that is due out in 2011. it is a good excuse to me at least

what i was looking for through this discussion was some kind of profound 'magical' aspect that applies only to the beltless magnums, but it really doesnt exist (i could quickly see it dissolving into a .30-06 + 8mm Mauser vs. 7.62x54R + .303 Brit argument.)
i guess the .300WM is gonna be it then, since there is not a terribly large advantage by going with the 30-375.