do not fly without learning how to walk.... taming a SLR with the heavy housing is not easy underwater... I have tried the D70 with ikelite housing underwater.. and boy.. decided not to get any DSLR for the time being and gone with the 7070....
suggest you practise more with the 7070.... its a very decent camera...
as for the strobes, if u ask me, its a must for balancing the light and bringing out the colors, but you will have to know how to use it, and how to place the light....
think before you goes off and burn 1K on a strobe, y dun u read more about underwater photography and learn more about your 7070 first ?
anyway... 8 more hrs to the dive of the year manado here i come!!!!