I am very pleased with my Ken Null SMZ. It is a slightly different variation on the shoulder holster theme.
http://www.klnullholsters.com/
A couple things I really like about it:
1) it is very comfortable - I can wear it all day long with no annoyance
2) the draw move is somewhat unusual - with a bit of practice it is very quick and easy - the gun comes out with a twisting move toward the target - if someone tried a grab on you without knowing how the holster works they would have a very difficult time
3) the holster does give good protection to the trigger guard
4) the design allows the pistol to move with you and your cover garment - I think this makes it more comfortable and it certainly helps keep the pistol from bulging out under the cover garment
5) inexpensive compared to other shoulder holster rigs
Downsides:
1) Ken Null says people carry full size pistols like this, but it really seems to me it is a system best suited for smaller/lighter pistols - I personally carry a SIG 232 this way
2) support comes from the rig attaching to the opposite side of your belt, so you do want to use a good belt - unlike other shoulder rigs, the holster tries to pull your pants UP
I have more info on this carry rig and some pictures in this thread:
http://thehighroad.org/showthread.php?t=309254
Agree with the others - in your situation I would be thinking "quick access to serious firepower" and not thinking "deep concealment."