Apples and oranges. The DSSD is the obvious work horse. With an ETA-2836 movement you can't go wrong. just double check to make sure it's GEN eta before it ships. The watch is indestructible and i'd put it up against a Cousteau Diver anyday. Although the Cousteau diver is labeled a diver, any diver's watch with chrono function is just posing in my point of view.
On the other hand, the Aquatimer/Cousteau line is very elegant and really classy. I love the design and have always wanted a slevin on bracelet. If workhorse undestructibility is what you prefer, go for the DSSD.
With regards to Prsist's comments on the DSSD being "hot" at the moment, i'd keep that comment relative. The cousteau/aquatimer is a classic and has been around a longer than the DSSD, on the other hand. So yes, at the moment the DSSD is very popular ON THE FORUM.. but in real life, i think both watches are a moderately rare sight to see on wrists. (be it rep or gen).
If you have to really choose between the two, and you're looking for a true diver's watch, go for the DSSD. If you want something a bit slimmer, less chunky, less heavy and a little bit classier (as far as sports watches go), go for the iwc.
Whatever you do, show us pics once the watch is in your posession!!
Good luck