Several years back, when I had a demo ( the chef of a local BIR let me watch him cook me a madras), after I got the meal, the chefs partner, who was responsible for 'front of house' (the two were partners in the business), told me that 'everything from the chicken' went into the base. I took that to mean stock made from the bits that would otherwise be waste.
I always make my base from stock made from a left over roast chicken carcass, rather than water, I was never sure it made that much difference until last night, my home made madras was nice, but not quite as good as usual. In my last few curries, I've been adding additional reduced stock, in the final prep of each individual dish, becauseI didn't have any when I made my base. Last night i forgot to add it in, the result seemed to lack the 'well-rounded' flavour I normal get. I can only describe it as tasting "thin", from a flavour point of view (as opposed to viscosity).
I think there may well be something in this thread!