I use that open D major tuning Amos - Vestapol, as I see it is called. I use it on my normal 6 string string mostly for fooling around at home ... but I use that tuning on a high strung guitar (Nashille Tuning) and I use it quite a bit. I set up my Martin Backpacker with that tuning ... it has two distinct qualities; 1) strumming chords for accompaniment it has an almost ukelele sound (or maybe mando when it's capoed up high) 2) I finger pick and play a melody on the fourth, thrid and second strings - that effect is cool because the 4, 3 strings being an octave higher then they ought to be give a pretty, music box sort of tone, then the high notes of the melody hit the 2 string which is an octave lower but still in the pretty music box sound range -- kinda turns your head a bit.

I like the fact that my limited banjo playing left hand fits neatly inside the 2 - 5 strings, that is my G tuning banjo chords and scales are all laid out in the inside four strings - BUT i get the added advantage of having that lower part of the scale when I use the 6th string. As a guitar player, I've always wished for a 6 string banjo - and I don't mean a guitar laid out on a banjo body - I mean a 5 string banjo, with a sixth string added to the bottom to give you the lower notes ....