Really wish they would implement in terminal C, but I don't think it is currently planned. Terminal A at BOS is much nicer anyway and I prefer to fly the legacy CO routes
I've been 100% hit rate since I started and I've been through somewhere in the range of 15-20 times... ^
Also I think I've only waited in line 1 time at BOS for maybe 2 minutes. Both times I've been through at LAX I was the only person and the half dozen times I've been through at EWR was the same.
ORD was the only "poor" experience I had because that day TSA had the precheck people routing through the same line as Premier Access which totally defeats the purpose...