Really it boils down to this...
'are the short mags worth it?'
Your velocities will approach standard magnum cartridges, the rifle will be 4-6 oz lighter than a long action, you will lose 1 or 2 rounds in the magazine. Some short mags have had feeding issues as well. Recoil will be higher than then '06- based cases.
But what I really like about the short mags is that you will end up with a rifle almost 2" shorter overall with the same length barrel. That makes a BIG difference in a carry rifle.
One of the biggest downsides to the short mags is that you are limited to the lighter-for-caliber bullets due to the very short mag length if you want to optimize performance. One can certainly load the long, heavy, high BC bullets in the short mag calibers, but much of the base of the bullet will take up valuable powder space in the cartridge. Of course this can be solved with a Wyatt's box mag modification.
A few years ago, I had need of one rifle to use for EVERYTHING- light weight, easy to carry, yet still capable of shooting 500-700 yards in case I ever get drawn for a sheep permit. When it came down to it, I decided on the 7WSM case and couldn't be happier. I built the sucker with a 24" barrel, McMillan EDGE stock, wyatt's box with center feed BDL-style bottom metal. Honestly, I don't think I could have built a better all-around rifle. It weighs 6.5 lbs w/o scope, yet will still group around 5-6" at 700 yards. I'm flinging the 140 grainers at 3400 fps (I easily got 3450, but got worried about throat erosion, so I backed off- as if that is going to make a difference :) ). That sucker kicks harder than any other rifle I own, but fortunately, I'm not recoil sensitive- so it's a non-issue for me. I would recommend a brake if you are recoil-shy.
I went with the 7WSM case due to it's shoulder being moved significantly forward of the 270 or 300 WSM, therby gaining a few extra grains of powder capacity. If you don't handload, stay away from the 7WSM, as ammo is notoriously difficult to find.
