With this airplane, the OS FX 1.60 would be on the low side of recommended power if you want to do anything other than simple flying or simple aerobats.

Pound-for-pound the OS FX 1.60 is a match for the Moki 1.80. Many people find that the OS is light and results in extra weight to properly balance the plane. This would definetly be true of the Moki 1.35. On the other hand, the Moki 1.80 seems to fit nicely and you can usually adjust components to properly balance without adding extra weight. An added bonus for the power hungry types there is the Moki 2.10. It only weighs a few ounces more than the 1.80 and adds almost 1 hp.

Some stats:

OS FX 1.60: weight 32.6ozs, 3.7hp
Moki 1.35: weight 30.2ozs, 3.45hp
Moki 1.80: weight 41ozs, 4.1hp
Moki 2.10: weight 46ozs, 4.95hp