I have one in my AR15 (I only have one AR15) and it would be my SHTF weapon if the need arose. I've heard of it "breaking" and becoming a single stage trigger somehow. But have any of you heard of (seen) a RRA 2 stage go down completely, do you think its not reliable for SHTF/serious use?

Best option?
ADCO RRA Upgrade

Thats an interesting upgrade. But has anyone seen a RRA 2 stage fail?

I have only witnessed one (that I'm aware of) RRA 2 stage trigger go tit's up.  It was in a tactical carbine class in the spring / summer of 2004.  I see a high amount of RRA rifles on the line during every class, so I'm assuming that most if not all of them have RRA 2 stage triggers in them (as all of the RRA guns that I'm aware of come from the factory with RRA's 2 stage trigger).

Match style trigger tend to have a high failure rate in many of the tactical carbine, Patrol Rifle, SWAT carbine, and other carbine related training that I've been in over the years.