Hey Glen, I have planed small pieces in mine but like skipard I have had to use double sided tape to attach to a larger board to run it through. Once you get less than about 8" in length mine gets kinda squirrelly unless you attach the small piece to larger stock. I have not tried this with acrylic and frankly seeing how acrylic turns on a wood lathe I would stand back near the circuit breaker the first time I tried to run acrylic through a planner.
I have had decent success doing wood that way using my 12" portable planer form Grizzly.
How repeatable? With my planer that depends on how thick a cut you're trying to take in one pass. Mine is pretty accurate and repeatable (within a run of several parts) as long as I don't try to take more than about 1/32" off on the final pass.
Ray
Ray