Actually, for big whites that need a tripod and a gimbal, there is no issue using an M body other than that the battery doesn't hold up very long running the IS in those big lenses. Where the tiny body does not work well is with more common telephotos like the 70-200L f/2.8 and the 100-400L. Handheld with an M series body, those are very unwieldy. I have an M3 and an M5 and have used both to good advantage on the 800L, but when the M6 II came out, I opted for the 90D, partly because of the better video in crop mode and partly because of the better handling with everyday telephotos. If Canon makes something resembling an M5 II with at least the video features of the 90D, I will likely add that to the collection because I do like the portability of the M series with native lenses.