I'd have to say the end results vary minimally if at all. That is to say that the use of a curry powder in the mixed powder, and in its eventual small quantity in a cooked curry, has very little effect on the finished dish.
Empirically, I am 99.7% certain that you are correct, My scientific and engineering background would like it to be otherwise, but in practice I think that replacing the curry powder with individual spices would have almost no
perceivable effect on the end product,
Slighly OT, I have just (almost) finished a lamb curry that I must have started before Christmas. Each time I came to prepare the next batch, I removed whatever lamb remained from the previous batch and cooked it afresh in fresh oil, g/g, spices and base. And each batch was better than the last. Tonight's was absolutely superb, both in texture and in taste, and I could not help thinking as I spooned ever more (oily) sauce over another piece of lamb and paratha that wanting to eat
more sauce (rather than picking the pieces of meat out of the sauce, as I confess I used to) really does demonstrate that one is "very nearly there" when it comes to BIR perfection.
** Phil (currently hoping that "Configuring Windows updates. 100% complete. Do not turn off your computer" will eventually terminate and my motherboard swap will have turned out to be a success. I forgot the auxiliary power connector on the first boot, and could not understand why the fans were all spinning their hearts out while the monitor was resolutely saying nothing)..