I built up one of these SP Cycle SP-M-016 frames in medium.
Ran into the same issues that previous posters had as well.
A four piston brake (Magura MT30) did not fit in the rear due to the seatstay issue. I sourced a Shimano MT-200 2 piston Rear and that fits fine with plenty of room. The Shimano was 300g, the Magura 255g. so a weight penalty there. Pink Bike is providing me some Shimano XT 2 pistons brakes to replace the MT-200 with. Unfortunately I'll have to rerun the brake hose when the XT rear gets here, but life is hard like that.
I also tried a generic GXP crank, and ran into issues with the chainstay clearance on a 32t ring. I tried to fix with spacers and eventually sanding down the tension ring, but I couldn't get it just right on tension. Close, very close, but not good enough. Ended up putting on a 28t steel ring. That was an additional 60g weight penalty. I also tried a hollowtech style 30t and had chainstay rubbing with that as well. I will probably not pony up $80 for an absolute black 0 offset 32t chainring, but we'll see.
Running the cable damping foam back into the chainstays was the most ridiculous part of the build, but she's dead quiet, so it was worth it.
It's about 25.5lb here with the i35 AL trail wheels and tires and a 1900g fork. At some point the new rims I ordered will arrive, and it'll drop to 10.2kg.
For the amount invested in the total build this is a great value.
It fits a 27.5 x 2.8 mid-wear Terrene McFly in the rear, with plenty of space.