Many SA trigger shoes for Shadow 1/2 replacements have both pre- and over-travel adjustment, so that is a considerable difference in overall feel. Also a lot of the SA triggers are set more forward for a overall longer reach, as well as being flat in profile.
Since I have spent so much time with Shadow 1's, when I set up a Shadow 2 in SAO I actually went with the 'shorter length' trigger model to better match the trigger pull length on my DA/SA Shadow 1's in SA mode. Again because I had gotten so used to that.
Theoretically the actual trigger break shouldn't feel much different if you're using the same sear and hammer, but the different profiles can still affect that subjectively.
