If I am planning to replace some old non-DIN rail units with some units, should I buy powered replacements or passive ones? As I understand it, the old C-Bus relays (non-DIN rail) did not supply C-Bus power, is that correct? If so, would I also be right to assume that whilst I could opt for the passive replacements it might not be a bad idea to use powered units and remove some of the old power supplies, given their age?