I find semi-autos to be easier to conceal in all conditions than a revolver. Not only is the grip equally difficult to hide between the two styles, but the revolver has the cylinder which is at least as wide as a full sized semi-auto with a 5 shot cylinder. I will grant the revolver carries well in a pocket but I am not a fan of such carry, I have too much else in there and it always seems the gun is turned around to the most difficult angle to grab it. A pocket holster helps tremendously but it only adds to the space taken up in the pocket.
I carry a Service sized Springfield XD 40 (4" barrel, 12 round magazine) all year long. With a slightly over sized, untucked T-shirt or something like a Columbia Fishing Shirt that is tucked in but "bloused" over the gun (less "blousing is needed if one is using a "tuckable" style holster), I have no problem concealing it at my waist line. At 6', 215 pounds I am not a small person but I am not really big either. It really does not take a lot to hide a gun from the overwhelming majority of people, with all the cell phones, multi-tools, pagers, i-Pods, and other things one can put on a belt, imprinting is much less of a problem today.