Pending on which grip insert you use, the crimson trace will fit the XDM.
As far as concealability, the SC will be easier to hide due to the shorter grip.
Pending on where you live, it might be harder to conceal the "M" as it is longer and will, in most cases at least require a cover garment which may not be feasible due to climate.
Pro and cons are about the same, meaning that pending on your point of view the differences between the two can be pros or cons.
I like a full grip and lots of bullets and don't mind dressing around the gun, so the "Pros" of the "M" don't bother me.
The SC has pros of being easier to conceal, but to me that's a con as I like the full grip.