I have a few comments... but I can't comment specifically on using a tuning in anger. I'm not even sure how that is done...
Originally Posted by Howardh
Howard, my apologies for possibly opening this up a little further than your specific question(s).
Originally Posted by Howardh
As with any instrument, including guitar, every tuning is a compromise. When contemplating an open tuning (GDGD in this case) with a more regular intervallic tuning (GDAE in this case), there are advantages which arise from each.
One of the main reasons for using an open tuning is the open string notes. If one is playing or singing in a style which makes great use of those particular notes, then it is easier to incorporate an open-note drone. One can play melodic notes above those open notes and the open chord.
A great advantage to a regular or semiregular intervallic tuning is that it is normally just a little distance away from all the chords and scales. The tuning compromises between a lot of possible directions. All melodic forms are equally easy, and equally hard.
The first question I'd have is, what specifically are you hoping to play? If it's a specific repertoire which is associated with a specific tuning, then by all means, why not use that specific tuning? If you're planning on playing more than a narrow specific type of music, though, learn the more general purpose tuning.
On guitar, I use four main tunings, two of them open for the drones (DADGAD and Drop D), and two for general use (standard tuning and full fifths tuning). I can noodle aimlessly in DADGAD and it sound like Irish traditional music, because I have the drone notes as a constant. However, I can't play the wide range of repertoire I can get to in standard and full fifths.
At this point, ALL my fretted instruments except 3 (a fretless bass and two guitars) are in fifths tuning; I can go from mandolin to mandola to six-course mandophone to eight-string electric guitar without having to switch gears.
My own recommendation to you, given that you appear to be just starting out, is to find some kind of instructional material which can give you a start on the instrument. If you can't find anything which helps with an open tuning, I'd recommend you go with GDAE, as this will give you grounding until you can get some confidence.
GDGD might not be the most common tuning for OM, incidentally. If there is a particular kind of music you like, I recommend you harness the power of the internet to your advantage, as there are websites where the particular tunings for different recordings are available. (No, I don't know of an specifically, but I generally find them on a case-by-case basis, searching for a particular album; it will build character if you experiment with searching through Google, so I will leave you to your own path of discovery.) Those recordings would be a resource for learning by ear, an equally valid way to learn to play.
There are also groups which discuss various forms of music in specific, and the people in those groups, both here in the specific music areas (like Irish traditional) will have more specific information about them than in the more instrument-specific areas and sites.
In parting, let me also recommend you read a nearby thread...
...which touches upon many of the questions you have.
Playing a hexed Eastman 614 oval-hole with scroll (hoodooed with MandoVoodoo!), a Flatiron 1SH mandola (original owner), and rocking my six-string Rainsong and Joshua mandophones and six-course, unison-tuned 12-string Ovation mandophone, with all of them in CGDAEB Full Fifths Tuning!