The 700 is what I use in low light as I can go up to a very usable ISO 6400.
The menu systems are almost identical, the features are almost identical.
And just to point out, the D90 is not a full frame body.
I'm not a Nikon user (Yet).
Being I have invested & tested much of Canon's best,
it might be time Nikon had a turn.
I could care less what's in the bag, as long as it works.
With the mention of the 5D2, it did take off like wild fire months before release. Not sure how many are 100% satisfied.
There was much whining from the older punks of the added video.
The 700 is probably equal of the FF 5D? No idea actually.
Low light noise control is preferred.
You also stated that's why it's better at it.
I think much of the average user in the $3k + range of spare change falls into this category of available light or are working on it.
Granted, crop sensor cameras do take advantage of FF lenses sweet spot.
I do it as well. The glass to do so in the F2.0 to F2.8 range is going to triple the cost and weight of what's in the bag from medium kit lenses if your really into low light action.
Needing a wheel chair at the end of the day might be the deciding factor.
Super Bike is next week.
We'll see how far off trail the 1DsMkII & 300 f2.8 gets me in mountain goat mode.
The D90 was simply on my list to try when it appeared.
I did the 30D when it came out.
If the D90 was ready the same time, it would have been a lighter load w/o video camera and support on tour to Europe instead.
So far, the single feature that has the highest priority is spot on focus.
I can easily deal with exposure glitch, but if the focus is off, it's garbage to start with.
If Nikon pulls this off at a higher rate then I'll add it to the pile or move on.
Cheers