OP, I had a friend ask almost this same question last week and this is how I responded. I’ve had both these scopes but surprisingly I’ve never had these two scopes together at the same time for any testing so take this with a grain of salt as it is purely conjecture based on independent experiences of both. I would say the Schmidt US 3-20 and March 4.5-28 compliment each other pretty well, meaning - performance characteristics between both scopes run pretty close. Eyebox, DOF and parallax fairly similar with maybe a slight edge to Schmidt. Optically, I’ve always felt the Schmidt fell off somewhat above 15x and think the 4.5-28 would actually perform better here. The March is shorter than the Schmidt making it more ideal for clipon use even though 4.5x might be a bit high, because of wide FOV I’m still able to see full screen of my Steiner C35 thermal and magnification does not appear to be pixelated at that mag. My final thoughts would be this - if you need 3x at the bottom the Schmidt is the obvious choice, if you don’t need 3x at the bottom the March IMO offers a better overall design. In the end I’d be happy with either scope. One last thing, I did not like at all the 18 mil DT35 turrets that Schmidt offers, in fact, I feel those are the worst turrets Schmidt has created to date, while the DT II+ turrets are their best. The March turrets on the original 4.5-28 are really good while the new Shuriken lock are superb, almost Tangent like in quality. Illumination on the US and March are about on par, neither are daylight bright by any stretch of the imagination but adequate when light gets low. At the current reduced price of the 4.5-28 I would not hesitate to say this is highly recommended.
Regarding reticle, neither are going to give you anything precise at bottom magnification. How do you plan on using the rifle at bottom mag? Are you tracking coyotes running by at 20 yards away kind of thing or?
