Hi All,
A couple of points arising from the discussion:
There's a tutor book with good adivice on buying. It's written by a guy called John Liestman, who lives in Texas, and is based around the idea that a player might not be anywhere near other players. You can get it from the Morpeth Chantry bagpipe museum, they take phone orders. Mention the author's name, it's not the only tutor.

D Chanter: the hole spacing is roughly the same as a D whistle. The biggest issue is the fact that it transposes everything- a tune written in D will emerge in A, a tune written in G will play in D, and so on. The D chanter is also quieter and (of course)lower pitched than the F or G and will easily be drowned out in a session.
The best session instrument is the concert G chanter. I like my F plus 20 cents chanter precisely because it's melodeon-proof, but that's rather selfish.
I sometimes play with a C/F melodeon player, and to do so I have to put a flatter reed in the pipes, which is a real pain. I've offered to tune his box up, but for some reason he's less than enthusiastic.

Cheers
Richard