I haven't used it, so can't comment. However, and you've probably read this in numerous places, fire forming 6 BRA from 6 BR is literally a no-brainer exercise to go through - AND - it still shoots lights out while fire forming. You need to speed the barrel up anyway, so just use the first 100 - 150 rounds down the barrel as fire forming rounds and be done with it.
Lapua brass is so nice in... well... everything, why would you want to screw around with anything else?
There's a thread on Accurate Shooter on it, some incredible groups at 1k using Alpha brass. If the price difference vs. Lapua ($120 vs $98 or so) isn't a concern that's what I'd go for. That said, Rocketman isn't wrong, fireforming is really simple too (unless you have an improperly headspaced chamber like me). But that comes with the added need to develop a fireforming load, and the extra barrel life used in that may or may not be an issue to you.
Fireforming is rediculous, but Alpha is a badass american company. I would say get th alpha and shoot like the wind. If you cant get it Lapua is good. No bad options.