Although the carbon 3rd can be a better substitution as it holds tune well,but it sounds bit brighter than B and E,not many fundamental guitarists can adjust to it.They would rather endure the tubbiness.Peter suggested a hybrid set to me,Dogal Diamente.I am still waiting for the strings to arrive to test on my 64cm guitar.
The nylon G is the thickest and it tuned lower than B and E,it feels slack from saddle to nut.It barely holds its pitch right from the begining.It gets worst when the guitar reacts to humidity swing and fingers static friction,not only G, the less noticeable ones also start to rebel,I am having hard time intonating the strings! The Yamaha came with intonated saddles on their guitars,quite good in terms of tuning G.
What I'd do is I'll give G a couple of more wraps on the barrel at the machine head,stretch and tune it much higher and leave it in the case overnite.It holds up a bit better but not a solution either.
2017 Karel Dedain Spruce/Maple (Torres) 64cm
1998 Yamaha GD 10, Spruce/IRW 65cm
1988 Alhambra AL 8, Cedar/IRW 65cm