I know there is a threshold that bases can meet but some are still far better than others and produce far better curries.
I have the tried Darth 100% Madras and base, Saffron Madras and base, Rajver Madras and base, UB's Madras and base, ifindforu base, BE Madras, Admins new base, KD base and curry etc. etc.
I think I've tested almost every seemingly half decent Madras and base sauce on this site. I'm totally sold on the SnS June 2008 Saffron evolution base. The Madras is great too, although nothing that new, I think the BE and Rajver style Madras would work similarly well. The evaporating off of the base and adding of water again and again makes a large difference. It really helps you get some oil separation in your curry, resulting in the perfect consistency.