There is also the strain on the electric start to consider, the heat management of the engine, and a few other factors as well - one being longevity. I have seen examples of people taking off up to 1mm and achieving the 10:1 territory, but with no known long term examples to go off of I would rather take a small step and see how it goes.
A mild bump in compression shouldn't do any harm, and should give a little extra oomph to the motor.
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