I was looking at latest generation Schmidt & Bender Exos just the other day - it was mounted on a bolt action rifle and is bulky and heavy. Image quality at 8x is usable but does look quite fish eyed, and with a a narrow eye box. It’s good a low power. But it weighs 600 grams which is 21 oz in old money. It made the rifle feel top heavy, and on a light combination gun it would just want to capsize all the time. The objective bell is also large and bulky. They also hugely expensive.

By contrast the little leupold 1-4x20 on a 1” tube weighs a bit under 300 gram so the whole package is much better balanced.

On my combination gun I did try a Doctor 1-6x20. Again it was too bulky and heavy. It was heavier than the 6x42 Zeiss 1” tubed scope the gun was built with. And again at 6x the image was not brilliant. I swapped it with the dealer for 1-4x of same make. It’s better, but truth be told I much prefer the straight 6x42 and I have shot plenty of deer and foxes snap shooting at close range as well as out to 250 yards.

For a 12 bore /223 combination gun I would first decide whether its really a shotgun that will you take that fox thats sitting out at 60 / 70 yards, or are you looking at as a nice walk about rifle for foxes etc but with a shot barrel so you can shoot that crow in top of tree etc. For the former a little red dot sight or open sights would work well. For the latter the ideal is a 3-9x36 of good make on a 1” tube or similar on a detachable mount. You should be able to get it nice and low. At higher magnification you still get a really good image yet wind it back for close range or take it off when stop by the duck pond when you are on your way home.