I've got the Hope V-Twin and it's everything you'd expect from Hope. It comes with the usual color options and much more accessible spare parts. I've got mine attached to a pair of M4s--their AM caliper. Weight with uncut hoses was a little bit more, but pretty close to Shimano CX-75 mechanical discs with full cables/housing. If you opted for the standard X2 calipers I'm sure it would be the other way around. Especially if you used all the tuning options(Ti bolts, Al backed organic pads, etc.). For me I gladly accepted the weight penalty for what I think is the best brake feel possible. The X2 calipers probably share similar power to the other convertors. My guess is that they'd have enough braking power, but fantastic modulation. The M4 calipers meet or exceed the braking power of a strong road caliper with new pads in dry conditions. The only niggle I have is that the mounting bracket is a little flimsy. It relies partially on the housing and hoses to support the convertor's weight. To prevent excess vibration you can easily mount a small strip of foam beneath your stem and either fasten it with hook and loop closures or tie wraps.