This lock first shipped in 2004 with the NewVaq. My fairly early vintage NewVaq357 (sn in the 5xxx range) is my daily carry CCW piece and the best gun I've ever owned...so I've been watching for ANY reports of Ruger lock failures.
There have been none to date...and I monitor a lot of forums.
I strongly doubt it's in the Redhawk. It's not been seen in the GP100 or SP101 yet either. The new Ruger LCR has it, and surprisingly it's exactly the same mechanism found in the SAs.
It appears Ruger "beta tested" the lock in lower-powered SAs on the assumption that most aren't used for personal defense, and the CAS/SASS crowd would "test" the bejeezus out of them with high round counts. After over four years with no failures, they finally in 2009 put it in an obvious self defense piece (LCR). By giving the LCR the exact same lock, the signal to those paying attention is "this thing has been heavily tested and you can trust it".
I think that was damned smart, myself.
(Note: by "lower power" SAs I mean less horsepower than the 44Mag/SBH, or the large-frame 45LCs. Those DO get used for personal defense now and again - against critters. And to my knowledge the Hunters and SBHs haven't seen the lock yet...the large-frame 45s might be shipping with the lock now but that's a recent development.)