It'll do what the load tables say it will, I'm sure. As far as accuracy, I doubt the case design has much at all to do with it.

Sorry to sound kermudgen (sp?) but so much of this "one cartridge better than another" gets me a little confused. Seems for a given case size, there's optimal bores, and those near it, and with known bullet weights you can pretty much guess how fast the thing will go.
Whether a cartridge performs well depends so much - if not almost all - on barrel, action trueness, and the actual cutting of the chamber, that unless you just get a batch of lopsided brass, it ought to do as well as the rifle made for it.
So maybe a good question is "how well made are the X-brand rifles?" If it's a good rifle, put together right, then any chamber should give you the expected speeds with a high degree of accuracy.
No?
Don't mean to sound pissy, but there's so much hype in the rags around the latest-greatest cartridge, when it's really just another powder/bullet package in a different wrapper.
What they should be doing is improving the guns, or the powder, or the bullets maybe, but the cases seem so unimportant within all of that.

And for the record, I think the ballistics for the WSM case look great. But they simply are what they are without mystery.
The 270 WSM will do what a 270 Win never will. SHould be grat for antelope and sheep, etc., everything the 270 is famed for.
If this new CRPF action from Winchester continues to work well w/o a hitch, I'd say that's a much more exciting development, for those that like the short mag idea.

The 270 WSM offers a SLIGHT improvement over the old 270 win, but not enough that either you or the game you are after will ever notice the difference. Using the standard 130gr bullet, the WSM beats the standard 270 by about 200fps, and at 300 yds, the wsm drops only 1" less than the standard 270. The wsm is new and exciting, and should be inherently more accurate due to the shorter action, etc. However, there are many parts to the accuracy puzzle, and case/action length are only one. Anything you can kill with a wsm, you can just as easily take with the standard cartridge.