I currently image with a ZWO533 as well. I am using a NON-Edge C9.25 with very pleasing results (with and without reducer). The small sensor on the 533 poses no challenge to the scope, and I get very good stars right to the edge of the image (no need to have the EDGE HD for this sensor in my opinion). I image with an EQ6-R Pro as well, fully loaded ( Eagle 3 computer riding on top of tube, Off axis guider, filter drawer, electronic focuser, camera, etc..), I get very, very good guiding. My main interest is in the smaller stuff, planetary nebula and galaxy mainly, so the narrow field of view is not a problem for me. My skies also seem to tolerate the high image scale as well (0,55" per pixel), and I am extremely pleased with my setup. If you want to image wider stuff, and/or you plan to get a camera with a bigger sensor down the road, going for the EDGE may be a better "future-proof" option. I've thought about the C11, but frankly, the results I am getting are so good I don't see how it would make much difference, the 9.25 already provides more than enough resolution and focal length.
Be aware, though, that as far as I know you won't be able to control Celestron´s motor focus (which I also have) with the ASIAir unit, so that might pose a problem. Hope that helps...
Edited by ERHAD, 09 April 2021 - 06:32 AM.