Thanks for the input ahicks. I've seen you quite a bit around the forums in my quest.
I'm new to gas except for the use of a blower, weed wacker and chainsaw lol . No tuning required, but I have nitro experience.
I've done lots of reading and from my understanding the gas evolution engines can be finicky.
I've considered the new 15cc from os max but the difference in weight from a 20cc is not much and more power to boot.As you said Prop clearance might be an issue,not sure till someone gets the plane or the manufacturer chimes in.