Here's my two cents.

First, I have the following engines: YS53, YS63, YS120FZ, YS140L,Moki 1.8, Moki 2.1

The YS engines of mine have been very easy to tune and break-in. The Moki's have taken a lot of break in, but are now very strong and reliable. However, I do run a cline pressure fuel delivery system with them. The YSs have this type of system built in along with supercharging.

As for power the Moki 180 is much stronger than my YS140. My YS140 delivers the most thrust when proped with a 17x8 ( I believe it turned at around 8800rpm) My Moki will turn a 18x8 Moki wood prop at 9000).

A lot of the pros use the Moki for scale applications, such as Top Gun.

Both engines have excellent throttle transition and reliability - if properly cared for.

FWIW.

Mike