I think there is a big differnece using extra hot chilie in the final curry, I use Rajah.
I've tried several 'makes' of curry powder in the spice mix, and as far as Rajah go, I've tried both the mild madras and the hot madras. I use the mild for two reasons: firstly any heat I need comes from additional chilie powder, and secondly I find the hot madras tasted slightly too strongly of bay leaf. The latter effect may be cumulative however, because by base has 3 or 4 bay leaves in it (removed before blending), although that's not much because I make the base in 5.5 ltr batches!