I've tried 1=9 plus 1=19 I have to say I am reasonably happy with either. I like the softness and warm tones that the Harman dev and paper give me. I try to keep the dev time under two minutes when ever possible. Normally aim to achieve three times emergence - dev wise. I prefer the warm look that this combination gives me.
I tend to work at a temperature of 27. I have found that the emulsion is very sensitive to damage though at warmer wash temperatures. I am still experimenting to find the right temperature level (wash-wise).
As for dirty trays - yup, this does seem to be worse with Harman Warmtone dev. I have to scrub mine like billyoh to get them clean afterwards. But we do have very hard water. So I would imagine that this makes it worse.
After all that though - I feel I will be sticking with this combination as it suits me fine.