What's worse, UT also combines all disadvantages of ST and DT. From the ST, it inherits greater sophistication and, consequently, lower reliability. From DT - a chance of confusion between the triggers (if you've never pulled the trigger of the wrong barrel, you've never shot a double with DT).
Good post, HD, but the above statement is somewhat of a revelation to me. I have shot two-triggered doubles for 54 years, and never did this. Moreover, I have hunted and shot sporting clays with others who were shooting DT guns and, again, never saw this occur.
I shoot several DT guns and several ST guns. I can swap between them with equal dexterity and never even give it a thought. What I mean is, it does not require a conscious effort to remember which type I am shooting, and there is never any confusion. There are many of my friends who shoot DT doubles that admit to having a bit of a problem shooting the rear trigger first, then going to the front with dexterity, but I don't.
Maybe some of us are wired differently or something. My dexterity with triggers certainly doesn't translate into superiority at breaking targets or hitting birds! I can miss them all with either type trigger arrangement, very handily!
All my best, SRH
