Troy is the only light weight land detector that I know of that can hunt in a driving rain storm. While most would not do that, here in Houston I've been caught in too many heavy showers. I would never take my Garretts (2500, Ace 250) out in those conditions even with a rain cover.
Also, do the other detectors have a lifetime warranty?
Those were the two reasons I decided to get one. It didn't hurt that most of the top end coin hunt participants in the two clubs I belong to seem to have a Troy.
In the right soil conditions I have found .22 shells at 6" and quarters at 12" with the stock coil.