Dan,
I can live with a cracked viewfinder, but a lot of people can't. If I can see to frame, I can use it. You should see the viewfinder on my little Ricoh FF1. I wouldn't even call it broken, as it's more like crushed. It still takes the same kind of photo's it did before my brother-in-law smashed it. My problem with buying and selling cameras like the Medalist with cracked or chipped viewfinders was that I would have to buy them very cheap to make any profit. An interested buyer would pick the camera up and say, "nice camera, but the viewfinder............" You can try to explain that the tiniest crack has nothing to do with the camera's photographic potential, but it seems to fall on deaf ears.
I do like the idea of a coated finder glass, but either way wouldn't really matter to me. Heck, I'd even take one out of correctly molded plastic. The worst thing on the Medalist cameras is if some moron got inside the viewfinder housing and messed with the tiny rangefinder prism wedges on both right and left side. Those prisms have the most brittle glass made. I've seen a few that were chipped up pretty bad. Other than the cracked viewfinder and fragile prism glass, the rest of the camera is pretty darn stout and fairly easy to fix. I know some folks complain about the Supermatic shutters, but I find them very robust and less delicate than either the Compur or even the Copal shutters. Plus, there are tons of spare Supermatic shutters out there for spare parts. Maybe that's why the well cared for Medalist is still ticking like a fine watch this many years down the line. Yup, they are still my favorite camera. That's why I would buy possibly two of the replacement finder glass, just in case I run onto a mint Medalist with a cracked find for cheap or one of my three Medalist cameras develops a crack.