Dick a lot of the groups that use the 882's probably and simply just don't boast of their finds on Tnet. Think about it, if your out surveying for the location of a new wreck site do you really want to advertise that fact here? Especially if your search is in an area that doesn't require permits.
There are some other huge differences in the equipment, with the cesium mags your getting 10 Hz sample rates (10 readings each second), vs. 1 to .25 Hz for protons, and they are far more sensitive. The biggest difference like you mentioned is in the software, not only does it help with a visual interpretation of the results, but it also aids in laying out the grids and following them. I've said it before though, a mag is not a plug and play tool. It takes time and experience to understand what the data is telling you and why. There is an art in itself to running a good survey and getting the best data possible. I'm not telling you anything you don't already know. If your trying to locate the main pile of a site it's one thing, but trying to find or follow a tiny scatter pattern is another.
The other thing your paying for by getting a good unit is training, service, and support. If AquaScan quit making the things, that ought to tell you something. Who's gonna fix it when it breaks?
There are also other options for getting a good survey without being the one to buy all the equipment, boats, etc., like renting it or paying to have it done. At somepoint trying to micromanage a salvage operation and doing everything in house on a small scale does not make economic or common sense.