In the interest of spreading knowledge about possible failure modes and assembly problems I am sharing my experiences.
1. Surface Module Holder - Mirror Image Assembly Possible:
It is possible to assemble this in a mirror image (we did). Despite having a puzzle like design to prevent incorrect assembly we put it together and glued it before testing it with the circuit board. It's glued now, and can't be used at all.
Solution: I'd recommend disassembling the communications module first and then using the board for the surface module as a guide to make sure you don't assemble it backwards.
2. Battery Tube - Easy to Short:
The + wire exits through a hole in the - terminal plate. We removed the + end cap to add batteries. The stress on the wire pulled on the plastic cover which separated at the - terminal side causing a short. This is a big problem because that end is epoxied in, so basically we have to throw away the whole battery tube and build a replacement. We are looking at what it will cost to get access to a laser cutter to make the fancy end caps.
Solution: It might be wise to run the + terminal wire outside of the battery tube rather than inside.
3. Battery Tubes Are Opened Very Often, But Very Hard to Open (wire as a battery pack for in-place recharging):
The battery tube is very hard to open for something that is being opened and closed every time. The battery holder should assembled with two additional wires in-between the battery connections (balancing wires). The end caps should take into account for this. There should be a standardized RC charging adapter in the main electronics package.
Solution: Basically we should set it up as a battery pack and run a standardized RC recharging connector out of the main electronics assembly. I am just looking into how to do this safely, anyone have any suggestions?
4. Batteries are Expensive - No Backup Waterproofing:
The RC community shrink-wraps battery packs which could be sealed with caulk. If the housing flooded additional water protection would be very nice.
5. End caps with syringe hole: It is not clear why this is left open, or how one is to seal it properly to achieve the 300' depth rating.