Hey Tom,
Where did you read that info on Nikon lenses? That's not my experience with them. If anything, Nikon lenses are far more compatible given that they are still using the F mount (and I've seen little sign of them changing that) whereas other firms like Canon have changed mounts quite a bit (so there's always the risk they could do so again).
Now when it comes to the built-in chips for AF-D/I/S/G, when changes like this occur, lens manufacturers like Sigma often provide a re-chipping service (it's in their best interest after all). So you just need to check how old a lens is and whether there have been any revisions.
Have a look at the following pages. It all seems a bit complicated to start with, but they should help:
Thom Hogan's Lens Acronyms
Nikon SLR Camera and Lens Compatibility
Personally, I'm still in a state of shock that G lenses don't have an aperture ring!
It does make choosing lens boards look easy though
One bit of advice, if you do decide to buy a "new" camera, make sure you get it in good enough time to learn how to use it properly before your hols. People often miss shots simply because they don't know how to work their cameras.