This is something I'm passionate about. When they took the tied gyro out of jet transport aircraft, I let out a long howl of protest. As a new Ppruner, I got flamed when I talked of reverting to a tied gyro with all the horizons TU.
That fact was that I'd spent hours and hours and hours, flying with (when there was a good bloke in the right) bits of cardboard positioned so that he could see at least two A-Hs and I could see none. Dirty weather, right down to minimums, time and time again. It's one hell of an instrument, and it doesn't often fail. Heh, Not often.
One night in a DAK, I repeatedly adjusted the rudder and waited for the horizons to settle to the T&S. Something was horribly wrong, and I beat a quick path to the stars. The T&S had gone kind of stogy, and wall well off. There was enough starlight to settle the horizons for the very dark ADF to minimas. A lesson learned.
After the BE Viscount, I often thought I might carry a battery powered T&S. It was to be some years before the tiny glider ones were developed, and by then I was behind glass, with a reasonably conventional standby. Another Heh! The first time I flew an ATR, the vertical info disappeared in anger. One 'dark and stormy' I lost all the glass, and really did not feel good about that one little instrument. I thought of the guy that lost it, while calling to ATC "Am I turning? I need to know if I'm turning." Some of his last words.
Such a simple instrument would have saved him...if he'd practiced with it of course.