Son #2 has been carrying a Sig 227 for several months now...likes it a lot...he's a former Marine MP, well versed in the M9 and accustomed to use of a de-cocker/safety. For me, it's a bit foreign, dropping that hammer each time you re-holster, tho I have no problems transitioning from 1911's (45+ years of carry as a civilian and in the military) to my Sig 226 and Sig 220.
In use, when finished with the drill, I de-cock then reholster, about the same as re-engaging the safety on my 1911's...the move is the same. Of greater concern is getting my 2nd shot into the group with the first DA shot. I've not really been successful in that regard. Good enough for defensive fire out to 15 yds, but not as consistent as with a 1911. I push for speed til I get palm sized groups shooting controlled pairs (two distinct sight pictures for a two shot drill).
If you like the DA/SA system, Sig (most any Sig) is a good choice. The grip is large, even on single stack models, to my way of thinking, but it's easily trainable if you stay with it. Of the dozen or so Sig's that I've been around, all were excellent right out of the box...DA trigger pulls were better than my much loved Smith revolvers, and the SA mode was entirely usable for any defensive situation. Sig also makes most model in SA only or DA only if that helps.
Glock makes a .45 as well, and if you like the trigger system and can live with the blocky grips, they offer a cheaper alternative. The two .45 Glocks that I had an afternoon with, both shot extremely well and with no malfunctions. If I were to carry one, I'd make it a point to begin and end each defensive practice session at the range, using the Glock in 'from the leather' defensive drills, just to imprint it into my muscle memory.
HTH's, YMMV, Rod