A ride report:
In a nutshell, my XL Phantom delivers on its promises. At speed it is super stable, the suspension is active and supple, and it's confident in steep descents.
Keep in mind my transition is from a steeper, smaller and more nimble XC oriented 26er, to a longer, slacker 29er, with nearly identical reach. Compared to my XL DW Flux (with 120mm Magura Durin Marathon), the rear suspension seems more progressive on the Phantom, not quite as supple, and it also seems to bob more during pedaling. I'm still looking for the perfect setup, but I can tell I'm really going to like this bike.
I may not have found the sweet spot for sag yet, but when just below 15mm (rider weight about 180#), it floats pretty nicely and IMO ramps up quickly. I was also able to balance things perfectly front to rear with the MRP Ribbon. I'm sure the 29er wheels and long wheelbase play a role, but I'm not going to try to analyze this if I can get the front and rear to work more efficiently over time.
I will try to decrease the sag a little and see how this changes pedaling bob and suppleness. I imagine a little less sag will improve both, I just hate how tedious it can be trying to get sag measured to the nearest mm.
I really like the MRP Ribbon Air. In my opinion Manitou had it right with the dual chamber Skareb years ago, and I'm really happy with it's performance. The Magura Durin has a platform adjustment that was really good and not intrusive, and I do miss that a little. I'm surprised and pleased with how little brake dive I have with the MRP. Maybe that's related to the HA or WB. I don't know.
Keep in mind that I also like to ride something different (better) than everybody else. Two (now three) of my biggest pluses are that it's NOT a Santa Cruz, NOT carbon fiber, and that the fork is NOT a Fox.
I'm still a ways from being totally confident on this bike, but finding a balance point so easily front to rear means my progression should be quick. I had a much harder time initially balancing the suspension on my Flux.
My $0.02.
G.