There is no compelling reason not to go with a M-A1. The right holster, belt, and holster position experimentation will allow you to conceal it (I'm 5'10" 150lbs. and carried one for years). That said, the S-A1 has a shorter grip and will print a little less and can accept M-A1 magazines (if you're into carrying spares). Over the long haul, you will probably wish you had a smaller gun - buying the S-A1 now might save you from changing to something like a Kahr or M&P Shield later. At least, that seems to be the evolution of carry for most people...
A lot of guys will disagree with me, but I think the C-A1 is absurd. It will print as bad as a M-A1 and slide length has virtually no impact on the carry experience. The only valid reasons I've seen cited in favor of the C-A1 is that it would weigh a little less than the M-A1 (but still more than the S-A1) and it would clear a holster faster than a M-A1 (probably an unmeasurable difference for 99% of shooters). For anyone who says they wanted the S-A1 but wanted the larger grip for their large hands (probably the most commonly cited reason for the C-A1 I've read) - I would say they should have just gotten the M-A1.
A lot of guys will disagree with me, but I think the C-A1 is absurd. It will print as bad as a M-A1 and slide length has virtually no impact on the carry experience. The only valid reasons I've seen cited in favor of the C-A1 is that it would weigh a little less than the M-A1 (but still more than the S-A1) and it would clear a holster faster than a M-A1 (probably an unmeasurable difference for 99% of shooters). For anyone who says they wanted the S-A1 but wanted the larger grip for their large hands (probably the most commonly cited reason for the C-A1 I've read) - I would say they should have just gotten the M-A1.
