I'm still undecided about whether to breed a 2nd Emerald Dragon. But if I do, no way will I go for a 3rd one. Four days to take each ultra-rare through breeding and hatching if you don't have gems to speed. Can't breed anything else in all that time.
And I keep thinking it will just be my luck that they will release a Gem-Fire hybrid right after the 45-hour timer eventually pops up over my Gem-Nature breeding pair.