Given you have ports for the S&S, the answer seems simple. Stick with S&S.
That being said, the Subal is a very cool housing, but as James pointed out, very pricey when compared to the S&S.
Another point to review is longevity of digital camera equipment. Two years ago, everyone was gooey for a Fuji S2. Now, nobody talks about it. Canon's full frame or larger sensor cameras are all the rage. You will be buying another DSLR body in another 2-3 years. Why move to another housing manufactor when you have all the goodies to set up your D70 easily and conveniently.
I am facing the same sort of quandry. I have become dissatisfied with the 1/125 sync and average autofocus capability of my S2 and would like the D70 in regards to autofocus speed and sync ability.
All that being said, I bet a faster, badder, bigger viewfindered(is it really a word) camera will appear on the market in the next year or two and you and I both along with all the personalities that post on this board will all be beating a path to purchase the answer to all of our underwater photography equipment needs.
That's it...2 cents worth.