It's very hard, for me, to hear some differences, as I don't have any suitable headphones, just smartphone earphones: Dave would sound great even with a winemaker's pipe with a funnel as a bell. Having said that my preference goes to blue, it seems to have more decisive tone with more harmonics too.
2007 Besson Prestige 2052, 3D+ K&G mouthpiece; JP373 baritone, 4B modified K&G mouthpiece; Bach 42GO trombone, T4C K&G mouthpiece; 1973 Besson New Standard 3 compensated valves, 3D+ K&G modified mouthpiece; Wessex French C tuba, 3D+ K&G modified mouthpiece.