I find that double drop D makes a nice compromise tuning between standard and dadgad and I'm using it more these days.

For the celtoid band I'm in I split between standard and open G, dadgad, or double drop D, though since it's mostly a vocal group I only really change things for my own benefit, doubting whether anyone else notices. The drawback of too many drones, suspended and diminished chords, common to my approach to dadgad, is that the keyboard player and I don't always jive, and I never am sure if there'll be keys.

In the guitar/violin duo I use standard if I carry one axe, multiple tunings if I carry more. Having just got a bouzouki (tuned in fifths), there's even more possibilities.

I really prefer to use lower tunings, even if it is just standard tuning intervals, because it provides easier transposition down for singers who can't make up their mind (including myself), and gets me further out of the way of other instrument's range. So even dadgad is more versatile when dropped a semi-tone or two, at least for me.

Peace, Mooh.