As I'm still on the hunt for the (my) perfect BIR CTM, I think a specific masala for CTM may in fact be a more common practice than I first thought.
I tried the Curry Barking Mad CTM recipe (Youtube: Curryholic1 CTM) and it uses a yogurt-and-Patak's based masala. While I had previously gone off the notion of yogurt in a CTM, I tried this and was very surprised by the results. I almost threw it out, when after adding the masala and base, it was so runny I thought "this can't be right". Then with a good 5 minutes hard boil reduction, turned out very very good.
-- Josh