I have used NiCad rechargeables for my camera and my Sea & Sea strobes for over a year. I followed the advice of Norbert Wu in one of his books on U/W photography: Radio Shack batteries and charger.
However, I read somewhere that use of NiMH batteries is a potential problem at depth due to the potential for hydrogen generation. I must confess that I have not followed up and discovered what the chemistry is that would produce hydrogen from a NiMH battery, though.
At any rate, I have discovered three things in the course of using these rechargeables:
(1) They recharge slowly and, so, a couple of rechargers is nice.
(2) In exotic climes you may need to bring a voltage converter and, if you have two chargers, you will need two converters (sorry for stating the obvious).
(3) I try to keep close track of battery usage to avoid having to use the charger unnecessarily. However, if it is not being used I tend to toss in a few batteries. I am not at all certain if this truly affects ultimate battery lifetime because I have had conflicting advice.
If I get inspired, I will check into the hydrogen generation problem and get back to you.
Scorpionfish