One thing I do have to add on your concept of dungeon design, a design like that is extremely gimmicky IF it isn't done consistently. I absolutely loath when I've gone half way through the game and I encounter an area that requires a complete shift from what I was doing the whole rest of the game. It just screams "gimick!" to me and makes me lose a whole lot of enthusiasm for the game.

Conversely if the areas are diversified as a general rule and you are constantly having to change your set up/tactics then each new area is an interesting challenge, not some contrived way to break up the monotony.

Woo! Short post.