Looks like a winner, Jeff. It reminds me of one of my favorite (as well as my oldest) knives, a Schrade-Walden skinner. The S-W has a 3.5 inch handle, but the pommel is an aluminum "birdshead" sort of thing that sweeps back, so it allows your pinkie a little more room than you would get from a straight handle that short; the blade is 4.5 inches long, and probably only about 1/16 inch thick, most likely 1095. It also has a dished out area just ahead of the grip, so the thumb has a perfect place to ride when putting a lot of downward pressure on the knife.
With the larger handle of the RAT, it would be super easy to control, and the edge is long enough to do some good work. And the choil, in conjunction with the file work, will allow you to choke up on the blade real easy for even better control. Piggybacked to a larger knife, this would be a perfect companion blade. What kind of sheath are you looking at, and have you fixed a price yet?