Steve S.: I was just about to say what Will has just said; he got there while I was signing in. Another point that hasn't been made (although it may have been implied)is that it limits the number of key changes within a given set of tunes. I think the problem lies more with melodeons than everything else. They tend to be the louder instruments, and also come with the bass accompaniment, which does rather tend to allow them to take the lead, especially if there are more than one, as is often the case. In fact, it is possible to play in C on a D/G box. there are usually a couple of buttons at the bottom of the rows giving the accidentals for the middle octave. A bit limiting, I grant you, but they are there. Use the bloody things! OK, you haven't got an F chord. Use your imagination. There are ways round this. Or learn to play a chromatic box - B/C, C#/D etc. or a C#/D/G box. Get something with more basses. Then you can play sets which run G-D-A, or G-C-D, etc. It makes things more interesting and more of a challenge. It also means that you can switch from major to minor in the same key, where the tune is written that way rather than reducing everything to stright G major, D major or E minor. It means that, possibly for the first time ever in an 'English' session, the C music in the Horse's Branle might actually be played as written. Well I can dream, can't I?
John Kelly.