Pork chops braise covered or uncovered?

Commercial pork has been bred to be so lean that it dries out quickly if not treated carefully. I would definitely braise it covered. I suspect that 300 degrees in the oven for an hour is too high for too long. I would suggest braising at 225, covered, until the meat test fork-tender. You can certainly remove your chops to a plate, cover them with foil and a towel to rest, while you reduce the sauce in the stovetop. The sauce will withstand additional cooking, where the chops will not. Once they're overlooked, you can't uncook them.

Certain pork chops (such as rib and shoulder) can braise beautifully if watched closely. As I would do with chicken hind-quarters, braise them, uncovered absolutely. Often with a braise, the liquid is meant to reduce and become a sauce for the dish. I would QUICKLY sear them in a shallow pan (you don't want to actually cook them), remove them, build your braising liquid in that same pan and braise just until they fall apart. As long as your chops have a enough connective tissue and a healthy fat content, you'll be fine.

Pork chops really need to be double thick to braise well. If they're thin cut, they run the risk of drying out.

Braising in a covered pot will raise the temperature at which the meat cooks. As the recipe is calling for you to braise a normally lean cut, the chop, that has already been hit with high heat, at 300 degrees, which is well above boiling point, I'd not cover the pot. Otherwise you're running the risk of drying the chop out. I'd also drop the temperature by 100 degrees, looking to reduce the braising liquid on stove top whilst chop is resting.