In summation: this is my new favorite mountain bike.
Reasons: Wheels and brakes.
Wheels: the wider Crest mk3 rims allow lower tire pressure which gives me more grip in the climbs and more cushion for the downhills. With reduced tire pressure I could effectively attack out of the saddle in the climbs without sacrificing much grip. I broke my old records for some local climbs already.
The rocky and semi-technical downhills were much easier due to the superb braking power offered by the Magura's. The carbon fork, handlebars and lower tire pressure sufficiently damped the vibrations so that I could move with speed.
The frame itself took me some getting used to. Initially I was very disappointed but found that most of the nervous feel was caused by an over-tightened headset. Once that was solved, the bike handles and steers well. I found myself attacking the hills successfully out of the saddle much more often than usual. Some of this can be attributed to the frame, but mostly the wheel/tire/pressure combo.
Frame: Ritchey Timberwolf size M (purchased for $300 due to defective paint), stripped, polished and chromed
Fork: Carbon AliExpress 27.5 15mm Thru-Axle
Rims: NoTubes Crest MK3's, stripped and polished, tubeless
Hubs: White Industries XMR 15x110 and 12x142
Spokes: Sapim CX Ray
Nipples: Sapim Polyax Alu 14mm
Tires: Schwalbe Thunder Burt Liteskin Tubeless
Crankset: XTR M980, 28x44
Cassette: SRAM XX1099, 11x36 (purchased used)
Chain: Shimano XT CN HG-95
Shifters: XTR M980, 2-3x10
Stem: Ritchey classic C220 100mm
Handlebars: AliExpress Carbon EC90
Brakes: Magura MT Trail SL with extra double caliper for rear
Discs: Hope 180mm silver
Brake-levers: Magura HC3 (purchased used)
Brake-lines: Uberbike stainless kit
Pedals: Crankbrothers Eggbeater 11 Ti (purchased used)
Saddle: Ritchey WCS carbon streem
Weight: 9.3kg with pedals
Cost: ~$4200
At a later time I will sand the seatpost and fork before having them painted to match the chrome frame. But for now, this build is finished.