In more than 20 years of diving with the Nikonos rig, I can honestly say I'd never heard anyone say that "every exposure had to be bracketed" and "focusing is a guess". The exposure system with this camera is very precise. Focusing is an estimate, but within the depth of field available at most common f-stops, even with the 35mm lens, out of focus shots are pretty much a non-issue. I do agree, for close-ups and macro, the framers are a pain, especially for skittish subjects, but with laser guides and cut down framers, I can still shoot in focus and do it more quickly than most anyone using a PS digital in macro. I have to agree, though, an SLR or DSLR is better suited for this task.
With the 20mm or 15mm lens, if you are out of focus, you have a problem bigger than being stuck with a PS (POS) film camera.
I've shot thousands of photos with my rig. I've can recall no problems with focusing or exposure in any condition and with any lens (excluding the ext. tubes and close up, which require those annoying framers.) When I take a poor photo, it is always MY fault. The TTL system is pretty darn accurate, once you understand its limitations. I bracket for asthetics, but the latitude with all but the most high-end transparencies makes this something I do only for a few critical "set" shots. I've had many more problems with exposure controls on my prosumer digital cameras.
I'll also admit that it would be nice to have a thousand shots on the dive, but I happen to enjoy the diving too. If I kept my eye glued to the finder the entire dive, I might loose some of that enjoyment.
I don't believe in hanging on to obsolete technologies (I dive with a computer, too). However, I do have problem with over-dependance on technology or subscribing to the 'latest' gizmo when the standard is still superior to what is most commonly available.
I own 7 digital cameras. They take great photos in certain circumstances. I ride a bicycle across the country every summer and my "kit" camera is an Optio W30. Fro what it does, it's the best camera I've ever owned. As an UW camera? It's just "okay". The aperture is too small, the focusing is erratic and requires patience and the lag, while short, is very annoying.
For the $200 it cost me to refurbish my Nikonos, I'm happy to avoid shutter lag, a "hunting focus" and reduced resolution. For $200, I would be happy for my kid to learn about depth of field, exposure, manual focus (an estimate of apparent distance, not a guess). When he's ready and wants to move on, I'll suggest a nice little digital rig for casual shooting. But, until he can swing $10K for a quality DSLR and housing, or until there is nowhere left to process his film, I'll suggest he stick with the Nikonos, if only for the quality.