http://www.longrangehunting.com/articles/338-edge-1.php
All you will ever need to know about the Edge.
From a case capacity stand point - 338 RUM, 338 LM, 338 Edge/Tomahawk/Mystic, 338 LM improved, 338-416 Rigby improved, 338 SnipeTac (or something close), 338-408 CT (yes 408CT brass is available).
If you look at SAAMI/CIP load data, you will find that the 338 RUM is not far off the LM and the larger Edge pulls away. There is no replacement for displacement.
Having spent some time shooting a 300RUM I can say that Rem brass shoots just fine. The parameters that matter are more then good enough to get you under 1/2 min. You should give the necks a bit of a skim but then I would do that for all makes of brass. The normal deburr is also needed.
When run at MAGNUM pressures, I was able to get at least 6 reloads from my brass with most going 8 to 10 reloads. So it is plenty strong for what it was designed for.
If you started with 100 cases, you would be nearing the end of the barrels life before you killed all the brass. That is strong enough for me...
I do agree that when pressures are ramped beyond magnum pressures, primer pockets will open up quickly but then should be be loading in proof pressure territory?
The biggest advantage to the Edge and other RUM based derivatives is the ease to put them into comtemporary actions. There are a few full magnum length actions that will feed the Edge no problem. All magnum actions will single feed.
The LM does require a larger bolt face and other mag mods. Adds quite a bit to the overall build for little ballistic advantage.
YMMV.
Jerry