Yeah, I think the proc watch is counting both buff gain and buff loss, looking at the combat log.
I ran the combat log through my proc-rate-calculation script, which produced the following:
Madness Procs: 130
Uptime Periods: 97
Total Swings: 3364
Proc Rate: 0.038644470868
Proc Std. Dev: 0.00332320936645
Proc rate lies between 0.0321309805098 and 0.0451579612263
PPM Values
-----------------------------
Mean: 1.00811663134
Min: 0.838199491559
Max: 1.17803377112
So, with the 2.3 speed weapons, it's extremely close to 1 PPM. Throw in the fact that the ProcWatches at 1.3 and 2.3 put forth very similar PPM numbers, I have no problem with labeling this as a 1 PPM proc.