Originally posted by axl I know it's not the right reason but: I like DL's double colour version. The one with silver top plate and lens mount... I wish K100D was coming like that.
Anyway. Out of those three, depends on what you already have (or don't have). If you own K10D go for istD. Similar layout and so on. If you have K100/110D I'd go with DS as a second body. It sports the same AF and you get advantage of having body with TTL flash system. If you don't care about anything above, and you don't mind only 3 (5 in DL2) AF points, go for DL in silver/black version. It's the nicest
Given the points you bring out, I would agree with this. As I said, the biggest issue is the TTL flash, and older lenses.
My approach is to always have a second body that does something different than the first.
This goes all the way back to my film days.
My first camera was a Ricoh XR2s. It was a good camera, but my second was a KX.
Why?
1) because it had a mechanically timed shutter, and only needed batteries for the internal metering
2) because the one I bought had a simple ground glass viewing screne, which did not go dark with long (or slow) lenses, like a split image did.
The two bodies worked in tandum, with fast film in the KX (low light and long lenses) and slow film in the XR2s.
A second body should always give you something different, so you can expand your horizons