I have a ZEN-50 that I currently fly with a Webra Speed .61. I posted a picture of it in my gallery of photos if you care to see it.

The two degrees of right thrust built into the fuselage is correct for my setup. I did not have to adjust it any further. I like the way the airplane flies although it does get small in a hurry! The airplane tends to come out a bit tail heavy but with the heavier engine, I did not have to add any weight to the nose. The retractable landing gear are a bit flimsy, but since I our flying field has a 400 foot paved runway, I have not had any problems with them. Having said that, I will probably rip them out this weekend!

When you fly the ZEN for the first time, stick to the recommended control throws. I found the elevator to be quite sensitive and was glad I resisted the temptation to increase the amount of throw as it did not seem like enough initially.