Just starting to shop for my upgrade to DSLR and am curious whether anyone sees any advantage in the D1x over the D100 (while UW).

Already know there are fewer housing choices.

Nemo

I use an F100 and a D100 side by side UW. The F100 is closely related to the D1x and so I base my opinions on that:

The autofocus is better on the D1x (although it is not as good as the D2h). This is particularly useful for macro shooting.

Plus D1x can TTL flash synch to 1/500th (only 1/180th on D100).

But I think the D100 is more suitable for UW shooting because it is smaller, cheaper to buy and to house. The extra weight and bulk of the D1x might be a pain for travel and in the water. Although in water handling is very subjectivce. Some people like small cameras others prefer big ones!

Alex

Alex identified the UW advantages to the D1X. Is it worth it? Probably not.

Faster AF is always better. I have an N90s. When the F100 came out, it was the same analysis. I didn't bother upgrading until I picked up a used F100, which I never housed.

The increased flash synch is valuable top side. Underwater, the D100 limitations only came up when trying to shoot fast moving objects where the fill flash may or may not reach the subject, e.g. sea lions.

There are many other D1X advantages top side if shoot in a studio.