pogre: I have serious Gerhardt envy when I see that room
Mold 71 is a very fun and useful mold, btw, and is essential for making doors and door arches (see the pic below).
scorch: 265 is actually the floor mold for the 1.5" floor pieces (MageKnight dungeon scale), 260 is the mold with the 1" flagstone floor pieces. The 1.5" pieces are useful for putting under walls and such, but will not give you a 1" grid to your dungeon if you are looking for that sort of thing (it's been my experience that the grid can be hard to see on the flagstone floor anyway, especially with my dark paint jobs). Mold 260 will also give you some smaller pieces to slot into those hard to fit spaces, though you could probably do the same cutting the larger floortiles down with a Dremel.
I held off on getting mold 45 a long time, as I was hard into a mastermaze dungeon-style phase. Since getting it though, I wish I had done so sooner
It adds a nice contrast in my opinion to the rough walls of the fieldstone molds. It was the mold I used for the golden brown "ruined chapel" section on the left side of my dungeon project here:
Bruce is coming out with 2 more gothic style molds this week, and another 2 within a week or so after that
Good time to be making gothic dungeons (they have a very dwarven feel to them imo).
Bruce has said that he is interested in making a cavern mold, he just hasn't figured out any practical way of doing so yet.
For round rooms, molds 72 and 73 are your choices in fieldstone. They are what I used to make the two rooms along the top edge of my dungeon with rounded walls. You'll notice if you look close that I "cheated" and expanded the diameter of the circles to 6" and 8" respectively by putting a straight wall piece in between the curved sections; it made the rooms more of a rounded octagon, but gave more space to play in and still looks just fine.