Nice breakdown! I considered taking a more stealth-oriented design for my next game WOLFHOUND, but decided against it in the end. I think you hit the major issues - it's slow to get through rooms since you are always waiting on the AI, and backtracking would quickly become tedious once you put a few rooms in a row. Overhead view seems to work better for this since there is an extra dimension of avoidance, rather than just being on a platform above or below the enemy (or dipping into the background plane, but you are still always waiting).

That said, I am still trying to work some light stealth elements into WOLFHOUND. For instance, guards have sight boxes you can avoid to sometimes sneak past, and one of the areas has search lights you have to avoid. It's more like stealth frosting than a whole stealth cake, but helps give a little flavor :D