So far I only have experience with the AX engines. I have bought 4 this past year (.46, 2x.55, 1.20). Every time I debate paying the extra money, and every time I am over joyed by my AX and the decision to get one. On less than perfect experiences (one?), their product support and warranty service were perfect and better than expected.

I have only had one dead stick in 16 gallons of fuel, due to an old plug in the wrong temperature conditions. I have sold off one plane/engine, the other three engines all start very easily by hand (have not seen the other one in a while so can't vouch for it).