Hello Deputy Tom,
I think the horizontal belt carry is great. If worn beneath a tee shirt or a suit coat, the knive is well concealed. The NY Special conceals a little better that the Agent because the Agent has a bigger handle. The two Dozier knives I have that use the horizontal sheath are not really long enough to carry IWB because there is not enough blade length to stabilize the knife in the pants. Also, I have some shoulder problems that make drawing from behind my right hip difficult. I had Dozier's sheath guy make IWB sheathes for my Agent and NY Special but I don't think they offer sufficient security because the portion that attaches to the belt does not hook under the belt.
I hope your friend enjoys his Agent and I hope you get one soon.
Bill