For those interested in the upgrade kit from Aquatica to upgrade a Mark III housing to accommodate a Mark IV, I have received the following information:
The housing upgrade kit is in its final stage of testing. If testing goes well, it should be available "next week", but certainly soon if next weeks estimated availability slips a bit. Pricing is going to be about $800 US. I don't know yet if the upgrade is something the user can easily do, or if it will be better to allow a service center like Backscatter perform the upgrade. I'll post more as that information becomes available.
Thanks to Rob at Backscatter, and Carolina at Aquatica, for helping me obtain the information gathered so far.
The great news to all of us waiting is that we should have something relatively soon! :-)