rorybbellows wrote:when you play B on a C chanter against D drones you will be 18 cent out of tune.
Yep. Something like that, in theory. This is analogous to using E drones with a D chanter, which is something I do on a regular basis. I
think it works (but if I posted a sound clip for others to judge you wouldn't know where the poor pipering finished and any inadequacies in the set-up began.....)
What I tend to do is tune the E drone slightly flat (using the slightly flat upper octave e). I'm also helped by the fact that the "normal" fingered b on my chanter is slightly sharp. This brings the e - b 5th interval a bit more in tune. Having said all that I wouldn't be surprised if there still weren't some intonation problems.
So maybe I have just got used to hearing those one or two "e minor" tunes sounding a particular way when I play them. I've read that keyboard players in the pre-equal temperment days realised that a tune played in C sounded different to the same tune played in B, and just accepted that difference in character.
IMO another caveat to the use of E drones is that suitable tunes are not all that easy to come by.