I have the 40 cal emp and the recoil isn't any different than my old g27. Maybe even slightly less. I carry it everyday and think its almost too nice to carry. The emp 40 is much more accurate that the g27 was at least in my hands it is. At 10 yards groups are less than an inch and even at 15 yards they don't go much more than an inch. So I think its a great gun and looks very nice to boot.
I guess the distance front to back is somewhat thinner. Didn't think of that. I would also assume that the aluminum vs. the steel frame on the forty makes it.somewhat lighter. Now I just wonder the the distance from the front to the backstrap is different on the forty as well cause it really doesn't seem different from the 45. Although its been awhile since I had a 45 caliber 1911 in my hands.