Not sure why you would want to?- I've got a d3s and would like 2 bodies, 1 is a bit restrictive.
i only use one body at a timeand not a pro but wanted FX a backup.
the more i read about the D3S performance at low light and in normal conditions it just seems so desirable.
the write up in the grays nikon magazine this mounth makes it sound so good while still pointing out the minor niggles.
if you need the low light and don't need two bodies (back up or whatever) then go for it.
i reckon i'd probably swap my d3 and d700 for a d3s problem is sometimes i really don't want a full sized body