As far as the sore finger try shooting low pressure shells if you are not doing that already. I use polywads 2 1/2 shells and do not have a problem. When I first got a Smith and used regular type & high brass shells my finger hurt also.
Single triggers are great as long as they are working. The problem is once they stop working or if the gun has a problem and has to be taken apart for any reason, one needs a gunsmith that has experience with single triggers. Everything has to be aligned exactly right for them to work. Just because it worked before taking it apart does not mean it will work when you put it back together.
I have only been dealing with these things a couple of years. Maybe some of the experts can give their opinions.