This is very nice work, I am no good at ASCOM drivers so I am re-using the ASCOM driver posted here.
However when using OpenPHD2 2.1.3a I was getting errors "ascom driver failed checking slewing" every time a guide pulse is sent to the mount?!?!? and I have to click the OK button on the error box that pops up.
Apparently a fix was added in OpenPHD 2.3.0 which allows PHD2 to ignore this type of error. When I upgraded to 2.3.1 the error still pops up but I now can guide. My challenge now is getting PEC working.