It's right pretty in't it?
I love my Yelli Screamy for it's slack front and snappy rear. Tho I'm an XC/trail rider not a hucker. The Yelli's weak point is it's a strong frame and a tad harsh for long rides. No snap there.
Not bothered about the Stanton's (marginally) steeper HA ... ETT is within 2mm, that's no biggie ... the question is am I really going to notice the steeper seat tube and the extra 10mm (or more .. the BB may be higher) in the chain stays?
(What's the worst that can happen .. drop 500 quid, transfer parts, if I don't get on with it sell it for 300?)