As an underwater camera the ergonomics of the S90/FIX90 "blow" the DX-2G out of the water
Care to specify how the controls of the FIX/S90 combo are superior to those of the 2G?
As for durability, seems many people on this forum swear by polycarbonate housings so there should be no reason for concern with the quality of the S&S housing, even if the perceived quality of that housing might be lower than the all alu FIX housing. Being smaller is a good thing, of course, but less so underwater (at least that's what I was told when considering switching to bigger cameras and worrying about the bulk). It's not as if you'll be stuffing the FIX in your BCD pocket anyways - especially not with the extras you're suggesting.
As for price, I may be wrong, but I'm assuming that someone who asks whether the 2G is worth $300 more than the 1G for a grand total of $900 will not necessarily be willing to spend an additional $300 on housing, and then a couple of grand more on wide lenses etc etc... At least not to begin with.
Wide end? There is no wide end on either camera underwater without the use of an auxiliary wet lens
True. But the 2G is still wider out of the box provided the user is not willing to invest an additional $500 on a wet lens.
The S90 is a Canon, the DX-2G is not.
No. It's a Ricoh. Very well known for their excellent compacts ever since the first GR appeared and celebrated by photographers around the world for their excellent handling and great IQ. Ricohs are quite often used as pocket cameras by professional photographers, whether they shoot Canon or Nikon. Says a lot, at least to me.
To bash the 2G because it's not a Canon is nothing short of complete ignorance.
By the time we add in the additional expense of external strobes, cables, trays, lights, lenses, the price differential taken as a complete system of the S90/FIX90 vs the DX-2G is small when you consider the improved capabilities and ergonomics of the S90 and FIX90 system.
By the time we add in all additional expenses up, you might as well go with a DSLR system, twin 80's, Halcyon regs, a scooter and all other sorts of redundant stuff. For someone asking advice on $600 vs $900, the FIX/S90 combo with an additional wide lens is probably not the right choice as it's $800 more.
Again you mention "improved capabilities and ergonomics". Exactly what do you mean? Wet lenses work on the 2G as well, as you know...
I wish my 5D mkII handled as well as my 2G.