"Barrel burners" are generally the over-bore chamberings. What happens is that as you increase the powder load behind a particular bullet, you get less and less of an increase in velocity until eventually you reach the point where you won't get any more velocity no matter how much more powder you put behind it.
How can that be? More powder equals more energy, and as long as you are burning all the powder in the load that energy has to push the bullet faster, right?
Nope, that energy also develops as HEAT!! You reach the point where little to no increase in velocity is achieved, but LOTS more heat is developed. That burns barrels.
Remember that it's the rapidly expanding gases that push the bullet down the barrel. Past a certain point (velocity of deflagration) you can develop more energy, but the VOD is a fixed upper value for any chemical compound.
That's why while a .223 isn't considered a barrel burner, a 22-250 is a (marginally) overbore semi-barrel burner, and a .223 WSSM will be a definite barrel burner.
The 300 WSM and 7mm WSM are the (approximate) equivalents to the 300 WM and the 7mm Rem mags in performance, but use a little less powder. They should have about the same or a little more barrel life, all things being equal.
Having said all the above, I personally wouldn't own a WSSM or a WSM in anything but an AR platform.
Loaded ammo can be hard to find and expensive, and reloading the wsm and wssm cases can be a bit of a pain. Not worth the trouble in a bolt gun when the long action mags are so much more convenient IMHO.
On the other hand if you want a .308/.243 performing round in an accurate sweet handling semi-auto, get a WSSM in an AR 15.
If you want magnum performance from an AR, get an AR 10 in WSM.
If you prefer bolt guns, stick to the .243, .308, 300 WM, or 7mm Rem mag (or other mag chamberings).