IF your main reason for buying the rifle is to hunt whitetails, the .270 WSM is a superb long range whitetail rig. For that matter, so is the .270 Winchester as made famous by Jack O'Conner years ago. I own the .270 Win and am very happy with it. Mine is in Ruger Mdl 77 (synthetic/stainless version) and shoots both 150 grain and 130 grain slugs very well. It does NOT like 140 grain anything, however the 130 and 150 slugs fill the bill.
Were I looking for a rifle specifically for whitetails, east, west, north or south, I would choose the .270 WSM. If I planned a trip to the Canadian provinces every year, I would probably lean toward the .300 WSM. The whitetails up there are not the same whitetails found in the lower 48 for the most part. They are bigger animals and on the praries of Canadian provinces, you have the possibility for some very long shots and the 180 grain bullets give you an edge. I am not particularly recoil shy anyway, and owned a .300 Win Mag previously. Factory loads for either will be a tad expensive, but both rifles will do the job. You could use the .300 WSM on whitetails and other larger game also. It basicially buplicates the older .300 Win Mag ballistics in a shorter, fatter case.
If it is a short range shooting and hunting <300 Yards then you might not even need them fancy short mags. a 25-06 or 7mm08 would do it real good and be even lighter in recoil. Shoot a 243 might even go it for you that would e the least ammount of recoil out there. One people often forget is the 257roberts a very very good deer cartridge.
Dont' forget the price of ammo!!! WSM ammo is PRICEY!!!! Why not get a 270 Win.,30/06,308Win, and with the cost savings,you can afford to shoot more. The last few boxes of 270 ammo I bought at Cabelas on sale were 12.99 each. Try getting WSM ammo for even double that! Just my 2 cents. By the way, I think the WSm's look really great on paper.