You asked if there are different DAO trigger designs? There are a number of different DAO triggers. Some are long and heavy with each pull like a revolver (the SW 3rd generation metal pistols like the 3953 9mm pistol). Some have two different weights of DAO pull depending on how far you let the trigger reset (example- Sig DAK pistols). Some have a light, short trigger pull with a short reset point like the Glocks. Some give you a choice of two different weights of DAO trigger pull- the HK LEM system. So there are a number of different types of DAO systems. The only way to figure out what works for you is to try the different types until you find one you like. Good luck.
Merry Christmas- oldandslow