Thanks J.
I timed the above procedure. It took 17 seconds before the pump stopped. Then after applying the brakes, it took 44 seconds before the pump came back on. Given this and in my opinion, less than I would want braking performance (similar to yourself) I am changing both accumulator and switch. I have checked wear around the discs and pads which are all fine, and bled the system, so I'm hoping better pressure will assist the brakes more.
AND I have, by chance, found a switch from a dealership who had one left in stock. I was going to ask about what they would recommend in the event there were no more switches to be had, but that got put on ice, at least for a year before this one gives up!