After getting several of the common species of snails (Nassarius, Margaritas, Turbo, Astraea, and Ceriths) none of them seamed to clean the sandbed of diatoms and such, making for a very unattractive diatom bed.
I don't think flow is the problem since the powerheads have moved the sand around until it all settled. Just the snails don't want to touch the sandbed, with the exception of the Nassariuses that just stay in a spot until food is present.
So went to the LFS, and found that they had several Conchs and was their first time handling them, so I decided why not! Got one that was roughly 1.5" and temperature acclimated him for a bit. Dropped him in and he went straight to work.
Sandbed looks almost like new with these deep trenches from the Conch. It did a very good job cleaning up the diatoms and it is slow enough that once it has reached a spot in the tank to work on, there is a new patch of diatoms growing where it had just left. So it is a constant supply of diatoms.
Given I do feed the tank twice a day so that could contribute to the diatoms never dying off after the cycle, but I have a Six-Line in the tank and they have a high metabolism so I just feel more comfortable feeding twice a day. Nitrates are surprisingly at 0 since I have removed the filter floss and have been feeding the Six-Line from a net (thaw out food, rinse, place in net, put net in tank for 5 minutes, remove when done) It keeps excess food from drifting around and settling in unwanted places.
From what I have experienced in the couple of weeks, Fighting Conch is a definite recommendation for any tank with a sandbed problem or not.