I own this lens and have used it on a Canon 7D mii and M5. As background, I've previously owned the Tamron 18-270mm VC and the Canon 35-350mm L. I like the concept of an all-in-one zoom for travel, hiking, situations like you describe, etc. I sold my previous superzoom lenses because I didn't use them enough. The focusing performance, noise, and image quality of the 18-270mm led me to use it less and less especially once I moved from an 8 megapixel 30D to the 7D mii. The Tamron 18-400mm has improved in all of these areas. It focuses accurately and quietly on both the 7D mii and M5 (like all adapted lenses I've tried on these cameras it focuses faster on the 7D mii). Image quality is not as good as the better Canon lenses, but I plan to use it mainly for travel that is not photography focused and when I'm participating in activities where the weight and bulk of multiple lenses is not desirable. Image quality also improves significantly when stopping down especially at longer focal lengths. The following photos of the Wisconsin State Capitol illustrate typical results stopping down from F6.3 to F8 at 400mm.
