arriving late to this one, but have ridden both and plumped for the 575.
I've been riding this for about 2 years with Pikes on, but after a summer trip to Verbier and the fact that most of my local riding is done on the hardtail, I have gone against the grain and stuck some Lyrik 2-steps on it.
Initial rides have been ACE. It is only slightly heavier, but the longer travel has made it into a big fast descending bike. it's not really jumpy ans the back end seems to soak everyting up (will be playing with rebound) but drop-offs and rockiness are handled with ease, desite any of my numptiness.
It seems that with the travel down to 115mm, the back sits up, firming it up for climbing, and once the travel is booted out to 160mm, it has a great feeling of sitting 'in' the bike for descents. The spec you've gone for sounds great, a real epic riding/ marathon bike, but it can go much beefier, with only a tad more weight gain.