I also like a continuous draw. I have an auto draw I got as part of a package deal but I never felt the need to hook it up.
For the "run away train" it sounds like you are drawing too fast and at shut down the flow surge upsets the gradient in the pan. Then as it boils more, you get far beyond syrup by the time the sensor at the draw off registers. I suggest you slow the draw speed (close the valve partially) to find a good balance. You likely want it to draw slightly faster than the boil will make syrup. As you go you can tweak the draw speed.
On my "continuous" draw it is not truly continuous, but once I get to syrup, I open the valve a little, if the temp rises I open slightly more. After a little while I find a good balance. I think my longest draw without further adjustment was somewhere about 90 minutes. My wife actually got that, she tends to make finer adjustments than I do trying to find the perfect flow. Then at the same time, you must fire the arch fast and at the right time intervals and must add defoamer everytime you fire the arch.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.