Yes, I use it. Both accompanying certain songs I sing and especially accompanying someone playing tunes as the drone effect at the bass end is similar to that used by pipes players. Hence the "Celtic" comments.

I also play baritone guitar. I'm having an eight string fan fret built as I type but presently use a wonderful inexpensive Alvarez guitar. As this is a large jumbo body, strumming and fast chording get muddled and lost, making it far nicer for slower picking, an excellent arena for modal tuning. In baritone B to B, detuning as per DADGAD gives you a modal A tuning that if played slowly works for English trad ballads like nothing else can. I love it.

I fully agree with the Carthys of this world though that standard tuning gives you the ability to conduct an orchestra. Modal and open tunings give you a string quartet. Martin of course conducts a string quartet like few others can.

(We had him and Martin Simpson play together at our local club last year and shock horror, he played in standard tuning! Might be a first....,)