I also took my 15x50 Canon to the store and compared it to the grey 16x42 SIG outside. Not an exhaustive comparison, but long enough to get some impressions.
And for reference, I previously owned one of the 16x42 but sold them shortly before buying the Canon so I didn't own them at the same time. After getting the Canon I definitely felt that they were an improvement over the SIG but I obviously didn't compare side by side until now.
One of the most noticeable things to me was the color. The Canon has a slight yellow cast to my eyes, while the SIG has a strong blue cast. I had never noticed the yellow with the Canon until now. Maybe it was the strong blue in the SIG that made it more apparent.
The blue in the SIG seemed stronger near the edge of the FOV while the Canon seemed uniformly yellow. With objects skylined, the blue seemed even more exaggerated. I remember seeing that in my personal sample of the 16x42 but I don't recall it having that darker blue near the edges like the one at the store.
The Canon also appear sharp towards the edge of the FOV, as I believe Roger Vine noted in his review. This sample of SIG is not sharp near the edge. Neither was my personal sample.
To me, the Canon view is more relaxed, brighter, and appears much larger. Simply due to the larger aperture and 1x less magnification?
I was expecting the SIG stabilization to be better, as that was what I felt was really noteworthy with mine but I didn't feel that it was any better than the Canon today. Maybe I have just gotten better at holding the Canon.
A local store has the non-HDX 16x42 and new HDX 16x42. I took my Canon 15x50 to compare outdoors, but I was really there to see the new 56mm scope from Vortex!
Most of my time and attention was on the scope but I did take some notes.
Conditions were hot and sunny. Lot of heat haze but I was able to look up into some trees and elevated objects.
I didn't notice such a big difference in terms of color or cast like I did with the non-HDX. If I recall correctly, it was more overcast that day though. Maybe that makes a difference.
I could see more detail at several hundred yards with the HDX than my Canon, in the center portion. That was looking at a shaded section of a fir tree. Better resolution or the extra 1x? Or maybe just better contrast, as the bark seemed more uniformly colored with the Canon whereas the SIG showed different shades.
The view was definitely more pleasing with the Canon. More relaxed and sharp to the edges. The HDX definitely was not sharp to the edges just like the non-HDX.
I didn't notice any difference in terms of brightness like I did with the non-HDX, but it was really sunny.
Unlike the non-HDX, I didn't notice any color fringing with the HDX but didn't go out of my way to look for it either. The non-HDX has very noticeable fringing to me.
The HDX still had blue around the periphery, but I think it has to do with the eye relief not working with my glasses. When I owned the non-HDX I was wearing contact lenses and never noticed the blue edge.
I don't know why I would see blue around the edges with the HDX and non-HDX but with both the blue gets noticeably brighter whenever the binoculars are pointed towards a brighter part of the viewing area. Could it be light from the edges of a lens?
I aggressively trimmed the rubber cups on my Canon and get full FOV. It's actually much easier to use than the SIG as crazy as that may seem.
The HDX seems like an improvement. And I still like the weight and size of the SIG over the Canon. The overall view of the Canon is still better to me especially with glasses.
I keep thinking about Roger Vine's review of the Canon. It has a nice flat image that is sharp nearly to the edge but it's not a beautiful image to me. Hard to describe but I can relate to his review. Very utilitarian I guess you could call it but when I examine the entire FOV, it's all sharp.
The HDX strikes me as being very functional. I can see what I need to, but when I examine the FOV it drops off away from center.
I was hoping that the HDX would blow me away right away. It didn't, but is an improvement over the non-HDX.
I may compare again on an overcast day.