I held off posting on this thread...
The advantages of a short action are completely in favor of the manufacturer, not the shooter. Long action length is a maximum of 3.34" and short action minimum length is 2.3". Thats just over 1" of bolt throw and it make a HUGE difference.
Cartridge shape (as it applies to smooth feeding), shoulder angle, powder capacity, bullet weight and overall performance all lie in favor of the long action. The only advantages to the SA are a more rigid action and shorter bolt throw...along with the less expensive manufacturing costs.
I'd be much more likely to choose a medium bore based on a long action over a short action for the sake of bullet weight and velocity flexibility. 35W, 338-06, 338WM and 375RUGER are proper choices. Better yet, move up to a magnum action mid-bore and experience a 375H&H, 375WBY, 375RUM or 378WBY. Talk about smooth feeding...it's Greased Lightning!
I only say this because I owned a 300WSM...a rifle I consider one of my biggest missteps in the firearms realm. I know people on AH have had success with the WSM's (thank you at
@WAB) but I consider them the exception, not the rule. Do your research and if you choose a WSM, make sure you have reloading dies and enough brass for your future. Best of luck.
IMO - If I were buying a mid-bore today, it would be a 375H&H, 375RUGER, 35W or 338WM...in that order based on ammo availability and bullet selection.