There is a game called Orders to Eagles that I’ve played at Little Wars outside Chicago, IL, USA which is similar to the scale you’re speaking of playing. O2E is *very* simplistic in many regards, battalions are 1″ square bases and have three statuses: good order, disorder, destroyed [removed]. It is an initiative based IGOUGO system which is also not my thing but it is a decently functional game.
To answer your main question about ground scale and how it looks, that depends a bit on the presentation and on your perspective. Once you get up to 1″ = 150 yards or greater most people seem to tend towards a simplistic presentation where only major terrain features are shown and they are done so using very distinct physical elements. This can influence your perspective of game play at this scale a lot. The real question for the player at this scale is if they are comfortable looking at the tabletop as a map rather than focusing on sticking their head down close to peer into the units and see the drama of individual actions. That is also perhaps the biggest difference between 15mm to 28mm players vs say 6mm to 10mm players. If you can accept the perspective that you are essentially playing on a live map then you can embrace the role of corps or army commander rather than getting hung up in small scale tactical decisions.
The Napoleonic project I am developing can be played at any ground scale above 1″ = 75 yards and some of my external play testers plan to run games at ground scales of 1″ = 100 yards, 1″ = 150 yards, etc… with 6mm or 10mm figures. It is notably more detailed than O2E but not heavy like one might think of say Empire. This project focuses primarily on command & control with very little tactical nuance.
One downside of many rules when playing as you describe is measuring weapon ranges – when musket range becomes a portion of an inch or several millimeters it becomes difficult and impractical to measure on the tabletop. Thus, I would tell you the most successful at these large ground scales conflate all non-ranged-artillery combat together and resolve it at contact. This allows radically increased ground scale without a lot of disputable and fiddly measuring. It is also consistent with the necessary abstraction brought by this scale of game.
That help any?