I'm glad to see this thread show up - I've been on my own on this up until now.
My 150 was built on 9/1 and I've been using it since Nov 10. We burn a continuous fire with no storage. I try to run small fires and loads whenever possible - only fully load at night. At first the boiler was running very hot and the fan was on a lot with the original high aquastat setting of 210. I've moved it down in stages, and now have it set at 192. This has made a huge difference, and the boiler now is generally always in a good range (side gauge 185-195). The fan shuts off more frequently and I get much more idle than before. Naturally wood usage is better also. I also insulated most of the pipes in the basement, and now the heat is going where it belongs. I agree with all the comments on wanting fan speed adjustments, but right now I've got the thing in good balance, and don't want to mess it up - I'll poke some more in the Spring when a mistake is not such a big deal.
Trevor, I agree with your #1 - the high fan speed doesn't seem to be effective, and for me only comes on when I've let the fire get too small. Perhaps it can get a fire going faster than low speed, but I need a good starter fire going first, otherwise high speed will put it out.
I'm new to Gasifiers, and might not be understanding what you mean in #2. My impression is that the low speed fan coming on is triggered by hitting the low temp, and that it's supposed to be ending the idle and bringing up the boiler temp again. What I just described is the way my 150 is currently operating, and this seems to be working well. Temp drops during idle, low fan comes on, temp goes up to around the high aquastat setting, fan shuts off. The heat output is consistent, and wood consumption is decent. Let me know if I am missing your point on this.