DADGAD is undoubtedly spot on for the new kind of Irish style of playing folk music(and a lot of British stuff as well). But I think Chris B is being reasonable as categorising this as a "Celtic twilight" sort of approach, given that is is very suitable for the modern "mythological" style, but not so useful for the approach to Irish music used by actual traditional players...say pre-1950. The danger that it is "too easy" has been commented on,too. That seems very true, you could so easily get hung up on the basic tricks of the trade involved in DADGAD that you might find it very hard to escape into another world, should you so which.
    Ian Carr is an interesting guitaist in this context, in that plays incredibly fluently in standard tuning, and can actual deploy most of the effects that you might be tempted to associate with DADGAD style playing. Now that is a skill.
Personally, I am pretty happy with standard tuning. Especially at sessions, where fidllers are liable to play "Sweet Georgia Brown". And then where are you if you're in some weirdo tuning! But, let's face it, if you want to sound like a DADGAD player, tune it DADGAD, It's that simple really.