I agree with BAX -- Both Master Airscrew & APC are reputable props & are used by thousands of modellers. Make sure that you balance all of your props & ensure that the shaft holes are true if you ream them.

From what I have read in this thread, I believe that you are over-propping your engine. A .46 LA can't effectively pull either an 11-6 or 10-8 prop. An 11-4 will work far better than the 11-6 where you want acceleration, climb & aerobatics. If speed is your need, a 10-7 is the max you should inflict on a .46 LA. Over propping will overheat the engine, increase radial crankshaft loads, increase piston side-load, increase vibration and shorten its life.

Single cylinder model engines are balanced to run smoothly in the upper end of their power band, & if you are overloading the engine with too much prop, you are pushing the revs down at full load & there is a good chance that you are out of the dynamic balance range -- that could be where your excessive vibration is comming from.