I havn't honestly looked at the ballistics of the 270wsm. Having said that, I highly doubt that statement is true. From what I've heard ballistically speaking they are pretty close as far as speed. In my opinion the 7mm bullet is superior from a Ballistic Coefficent standpoint to the .277. Bullet selection is greater, in my mind I don't think I would even hesitate to choose the 7mm over the 270wsm for those reasons. About the only thing the 270 would get you from what I can see is possibly a lighter rifle, and more kick...
I forgot to mention that the WSM's have been notorious for having feeding problems as well.
I think the 270wsm is just the latest 'new thing'...not better than the 7 mag. Ballistically it fits between the 270 win. and the 270 wby mag. I just got word that the 270wsm submoa vanguard I've had on order for about 2 months probably won't be delivered for another 6 months so that chambering must be flying off the shelves. Lots of hype right now for the 270wsm but the 7 mag will still be standing long after the furor is over.
The big talk is the ballistics out of the WSSM's........if I'm not mistaken they came out with one in the 270 this year, and is supposed to be a ball of fire...ballistically superior.......I'll see if I can find out more.....
I'm not aware of a 270 WSSM...I've seen the 25 WSSM and would guess the case diameter on a 270 WSSM would have the same diameter as a fire hydrant---should be a feeding nightmare out of the box.