How would the velocities of the .45lc, .454, and .460 out of your 16" barrel compare with the rounds being fired from the barrel lengths offered for the S&W x-frame?
Any idea on how successful the .460 has been for S&W to begin with? I would think with a serial number guide, you could get a general idea for the numbers made, and therefor general demand for the caliber.
One additional thought, that may not factor too much, all of those rounds are fairly expensive handgun rounds. Even .45lc is almost a buck a round last I checked.