Rik,
Flavour, yes, but what about scent. Surely that disperses, and isn't a scent trail just as attractive as a flavour trail? I agree that water-soluble has the advantage of both, but is the dispersal efficient in still-waters.
Ps. I've put a question to you in the 'D-rig' thread (Birds Nest) that I'd appreciate your thoughts on.
Clive.