I have the .270 WSM in the Winchester M70 Classic Stainless.
As for the cartridge, it's kinda cool. It has a bit more punch than a regular .270, but I yet don't know if it's "performance" on game as I have not yet hunted with it.
As for the rifle, it's pretty accurate. I would say about an inch at 100 yards. My major complaint is with the factory synthetic stock - which is junk - like most factory plastic stocks. I will likely buy a McMillan or HS stock in the future, have it pillar and have the action glass bedded with the barrel free floated. Then I'll have a trigger job with the pull set at about 2.5 pounds. The only other thing that I might do is have the action polished to make it smoother.
Granted, this is quite a bit of customized work, but, in my opinion, is worth the money.
Keep in mind that, since Browning and Winchester are owned by the same parent company, I believe that their synthetic stocks are essentially the same.
As for the Tikka T3, I wouldn't get it in any WSM because the action is a long action.
You may also want to consider HOWA - I think that they now offer the .270 WSM in a synthetic stainless model - although I would still get an after market stock.
Zachary