As you know I have a Metrolux II timer and if you have any questions please feel free to ask. I have used several timers before and this is by far the best timer I have ever used. Granted I have not used RH Designs set of timers but I have heard that they are excellent. But with the Metrolux II you can buy realatively cheap acc that will allow you to have a small densitometer and a shutter checker. You can get a probe that fits in the head of a cold light that will adjust for voltage fluxuation and if the cold light starts to get to warm. It will make the timer count slower or faster.