I have both the 270 WSM and the 270 Win. I reload so ammo cost and availability are of no concern to me. The 270 WSM will give you about the same gain over the 270 Win. as the 300 Win Mag has over the 30-06. This about 200 FPS. Enough to matter in the real world? Probably not but the numbers are there.

I only tried the 270 WSM because I wanted to try a Short Mag and also a Savage accu-trigger rifle so I combined the two and got the Savage Varmit model in 270 WSM.

Also I wanted to try one before DD does.