Adrian,
yep definitely got to keep the spice mix/mix powder unchanged. i'd certainly keep the tomato juice for the madras.
a pic of last nights madras sauce. i used: 2 tbsp oil, 1.5 tbsp Panpot's Garlic/ginger paste, 3 tbsp tom puree (normally 2 but current base has no tomato) in 3/4 cup of water (for the emulsification), 1 tsp LB spice mix (any of the good ones are just as good ie DD's), 1/2 tsp rajah curry powder, 1/2 tsp bassar, 1/4 tsp chilli powder, 1/4 tsp salt, 2 tbsp original onion paste. and of course my new found ingredient thanks to CK and Adrian - passata (4 tbsp). i'd run out of chopped fresh "frozen" coriander unfortunately.