I tore my ACL 5 years ago skiing. For me, there was no pain from the actual tear, but I had a lot of swelling within the knee and was on crutches for 3 weeks while the swelling went down and I was able to walk on it again. Even then I had to be really careful how I stepped or it would start to give out. That is one the strangest and most wrong feelings, when your knee shifts and moves in directions that it is just NOT supposed to move.
I ended up having surgery because I just could not trust the knee and at 25 I didn't want to be limited in the things I could participate in because of the knee. I had the allograft (cadaver tendon), but I didn't have a choice because my pateller tendon was too small to use part of it for my ACL. one of the main advantages of the allograft is the much faster recovery time, and one of the main problems with the pateller tendon is many people have a very hard time kneeling after the surgery (even years later), so given what you and hubby do, if he does have surgery that is something to consider.
As for deciding to have surgery or not... I know people that have done both, and people that waited years to have it fixed. I think that the biggest deciding factor if it isn't interfearing with everyday life is why types of activities he wants to participate in....generally you can do straight line activities (running, biking) things that require pivoting can be more problematic (golf, soccer, skiing, basketball, hiking), so it depends on what you husband likes to do and if he can do these activites they way his knee is now.
Good luck!