My Welbars were derived from dark egg laying Welsummers (from Whitmore Farms) and their eggs are indistinguishable from pure Welsummers or (my) Black Copper Marans. The OE's I produced this year are F2's, 3/4 Legbar and 1/4 Welsummer. I was worried they would not be very dark, but the pics my customers have sent me are nice and dark. I'm sure they will fade some, as all dark egg layers do.
I have a single Rhodebar in my Legbar pen to produce light green egg layers, if there is demand for them, otherwise we will eat those eggs.
Molly 's eggs started as olive color, and becomes olive and green. She's a really good layer, about 6 eggs per week. That's why the eggs cannot keep their dark color. Same thing happens to Brownie, her eggs from nice blue color become light blue. She laid 7 eggs per week until she went to broody.
I like light green eggs too. But I really love Molly ' s personality, so I'll take the welbar / legbar girl and hope she will be as a great cuddler as Molly.
Good luck to your big presentation tomorrow. We are too far to join you.