I have to say that I have made several different batches of base sauce/gravy over the past 2 years, and the curries I have made from them haven't been anywhere near as good as the ones I have made without a base sauce. Maybe I'm not cooking them on a high enough heat? maybe its something to do with the ingredients, I don't know.
I posted a Chicken Kashmiri Masala on here a while ago which I cannot find anymore, but it used just fresh ingredients and no base sauce, and it was one of the best curries I have ever tasted....
I'm not knocking base sauce, but I think in future I'll leave it to the BIR's to produce, and I'll continue to make my mouth watering curries without it..