Wasn't it the build quality of the S2 and S3 that restricted them
to those applications? It seems to me by putting a (more or less)
weather-sealed body around a wide DR sensor like this, it would
also be good for landscapes, except the resolution is kind of low
for those.
The build quality of the S3 is acceptable, but it feels cheap and plasticky when compared to the alloy bodies like D200 or D2x. The build quality is ok for studio work, portraits, and weddings (not in rain though).
Compared to the S3, I'll feel much more comfortable to bring the S5 to the mountains for landscape shots.
Sounds like a dream come true. Even with the D2X I just don't trust
going straight to JPEG even though this camera certainly needs less
PP than my first DSLR, the D70.
I love using the S3's F1 film simulation mode for potraits. Wonderful skintones right out of the camera. To be honest, I seldom need to post process the JPEGs. If I really have to post process the JPEGs, mostly it's just sharpness and white balance adjustments.
Here's a S3 review with nice sample pics
http://www.noendpress.com/pvachier/cameras/fuji_S3.php
Though the S3 may sound like a dream come true, it is very sluggish. For me it's ok because I shoot portraits, still life, landscapes, and cityscapes. But it's definitely not a camera for sports.
I hope the S5 will not be sluggish like the S3.
Do you think I could make high quality, highly detailed landscapes
at 13"x19"? That's my personal benchmark for my amateur landscape
photography, and the D2X does that with flying colors, and then
some, I'm sure (but haven't gone beyond that personally).
Many suggested that the S3's SuperCCD has resolution of 8 to 9MP of a regular sensor. So, if your D70 can give you acceptable 13x19 prints. You'll be ok with the S3/S5. But it won't be as good as your D2x.
After reading your post and several others in this thread, suddenly
I'm very interested.
To me, switching from Nikon to Fuji feels almost like switching from PC to Mac

I have fallen in love with the Fuji color, film simulations, dynamic range, and stunning JPEGs right out of the box.
If you hate post processing, the S3/S5 should be on your wishlist.
I find that the S3's a bargain at the current price. If you can live with its sluggishness, it should complement your D2x very well.
However, the S3 only supports D-TTL flash.... so, if you've invested a lot in Nikon's new CLS system for your D2x, you might as well wait for the S5 which supports i-TTL
Anyway, here's a quote from Steve's Digcam review on the S3 -
The S3 Pro makes full use of Fujifilm’s extensive color film expertise. Rather than force photographers to shoot in RAW mode and spend time on an extensive workflow process, Fujifilm has introduced Film Simulation Modes, dynamic range presets and color space selection. Once the photographer is familiar with these settings, they will be able to produce JPEG images straight from the camera, which require no post-production. Photographers can choose between smooth, extended tonality and natural skin tones, or the dramatic impact of highly saturated color. The Film Simulation Mode is the equivalent of changing film type to suit shooting conditions, and achieves this at the touch of a button....
.... The bottom line: The FinePix S3 Pro is a camera with two personalities. In Standard D-Range it produces excellent results both at 6 and 12 megapixel image sizes, but doesn't justify its $2,500 price versus the competiting dSLRs. Set D-Range to Wide and the S3 is transformed into an amazing portrait-taking image processor. Although a bit sluggish in this mode, its results may better satisfy the needs of your portrait business than anything else available today, more than justifying its price.