I have the same advise. If you want a housed SLR, go for F80 with Sea & Sea NX-80. It is one of the cheapest options, with the right technique, you should be getting pictures similar to that of David Doubilet or Chris Newbert!!! I heard that David Doubilet is still using F90X, it is slower than the F80 in terms of focusing. If he can do it with F90X, I think you should be able to do quite a bit with F80. Try not to get too hung up on equipment, keep it effectively simple!!!
For the housing, remember to go for the brand which is the most convenient for you in terms of getting it serviced. Imagine you have a big trip next week and you suddenly realise you have a small problem in your housing, I don't think you would want to send it to a far away place to get it repaired.
As for digital, I will do the waiting game. I am totally satisfy with film now and will only go digital when the price is right. D100 is very nice, but it is too expensive to bring it down underwater.
Liang