Lemme try to help this bit by bit
Wont that gimp the speed to the point where the extractor can't function through all stages without some sort of complicated redstone control mechanism?
Depends what the overall power of your source is. But just to be clear, nearly everyone these days uses a very simple mechanism to flip a CVT constantly between
two stages: 1 for "minimum torque" and one for "pure unalderated speed". (You can argue for three stages, for 256 nm torque, but whatever.)
I'm talking about whacking one engine down and how the microturbine has copious amount of wattage but due to it's low torque it isn't able to run all 4 stages of an extractor alone with no funny business of switching gear modes (automatically or otherwise).
At a 256:1 ratio the speed becomes 512 rad/s and at 512:1 it becomes 256 (less then a steam engine).
The 256:1 ratio was an example of a higher-ratio gear. It would not apply to your specific micro-turbine scenario: a CVT would be best, and its very configurable with redstone signals.
Way too slow for any stage of the extractor
I think you already know this, but just for clarification, keep in mind that only 2 stages have "minimum speed". The stages with "minimum torque" could be run at 1 rad/s. Which would not be fun for reasons you've observed.
The micro turbine could blister through stage 2 and 3 though as they don't seem to have torque requirements but it just can't get through stage 1 and 4 without going super slow.
Right. This engine, while very nice, does not provide enough
overall power to produce
high speeds at minimum torque (on the extractor).
And that's why I told OP not to get hung up on the wattage, it's not the determining factor as to whether an engine can run a machine smoothly. You need to look at their specific torque/ speed requirements.
Close but a bit off. Since speed is a function of power(Wattage) and torque, the more power you get, the more speed you (can) get. Hence, running your extractor with a Gas Turbine is a much more pleasant experience than running it on the microturbine. Once you gear the gas turbine to perfect "minimum torque" for stages 1 and 4, it blisters through stacks of ore like nobody's business.[DOUBLEPOST=1401588014][/DOUBLEPOST]
Is torque ever relevant to speed, our is it just a simple will work/won't work type thing?
Sorry if this information is wrong, but I seem to recall that the compressor machine, which makes diamonds out of coal, functions faster with huge piles of torque.