I am at 910' above sea level and run a 15x4 apc on Saito .82 , spool up is slower but manageable. and you can climb, hover, or slip withing a click of each other. Clearance is an issue with 15x4
My Twist is on its second rebuild after i gave it away.
Problems with the .82 for me was short flight times. I have had the .82 and the .91 on the same plane and the .91 will fly it longer. And yes I know how to set up an engine.