CGDA is working for me. Tuning in fifths will feel natural to anyone who has played violin, viola, cello, mandolin, mandola, octave mandolin, etc. You end up using each finger for it's own note in the diatonic scale, and the patterns work across all of the strings.
If you're worried about tuning way down to a C, hold the bass out away from your body and play the low C. It feels loose and looks sloppy. But hold the bass against your chest and play it and you'll feel this powerful low vibration coming from the string. This feels very natural, in a way that electric instruments don't. But, you'll need a good, clean amp that can amplify the lows. See my other posting about the Acoustic Image Contra. It sounds really wonderful .
Down around 30Hz, the lowest notes take more time to develop tone, so keep the fast licks for the upper strings.
I can testify that holding the strings down sharply above the nut adds significant volume and sustain to the C and G strings (in CGDA tuning). I have ordered a string retainer bar to help with this.
Regarding tuning the high G up to an A: I've already broken 3 high strings and have started detuning when not in use. If this doesn't work, I'll search for a bulk source of strings.
