For the record I prefer concealed hammer vs. shrouded hammer models.
Pros of shrouded hammer - option of cocking the hammer for SA mode
Cons - design allows for lint and other debris to collect in there
Pros of concealed hammer - design doesn't allow for lint and debris to collect
Cons - as you mentioned DAO which some find to be a negative
Personally, I find another advantage to the concealed hammer version and that is due to the design I can get a higher grip hold which allows me to shoot these guns much more accurately than either the traditional version or shrouded version. Being a fan of DAO in defensive guns, particularly with snubbies, I see no need for the shrouded hammer design. I shoot my 640 Centennial better than my 37 Airweight by a large margin. The bottomline is, do you want the SA option? Mike