Doug is right; That C6 is probably the "best" single tuning of the hundreds invented and the dozens regularly used for lap steel. It's a classic tuning that a lot of classic sounds are based on. If you're going to invest a lot of time in it as a new instrument it's probably worth the time to get really familiar with it; figure almost the same time it took to get where you are now with G tuning.
BUT, if you're going to double and continue to play dobro a lot of the time, you might consider some kind of G6 tuning, which would mean adding an e string (or two)in there somewhere and losing one of your low strings. The big advantage of this is that you will stay oriented since most of your strings, and your basic major chords, will still be where you're used to them, and many of the licks and slants you use now will still work once your right hand learns to skip the e string when you want to.
I use GBdegbd'e' on my 8-string, and like that top e' string a lot (I think of this tuning as combining dobro and Spanish guitar tunings). I had a 6-string set up for awhile with the highest 6 of that set; I didn't miss the low strings as much as I expected to (depends on what kind of group you play in), and there sure are a lot of chords in 6th tunings, especially if you use string bends. You might also try Bdegb'd' or Bdgbde'
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John Kavanagh
D-8, acoustic 8
[This message was edited by John Kavanagh on 21 January 2001 at 11:34 AM.]