Those of us who shoot the 270Wby often wonder what the allure of the 257 is. The 270 was first (the first, in fact) and it's just slightly flatter and faster with equal weight for caliber bullets (comparable SDs), so it truly does everything the 257 does, and a bit more.
To your question, IFeelRecoil, I haven't tried RL22 in my 270Wby, having found IMR7828ssc and MagPro to be excellent performers. I'm sure it would be fine, but my use of it in 300Wby showed me a lack of consistency so I dont use it much at all.