Dave,
I've heard and owned both drums and prisms. I'd suggest drums across your front 3. Get either the classic 6's or a pair of 4's. Having matching 4's across the front is a wonderful combo. I know you like the look of the woods, but the ceramics and marbles can be played at higher volumes cleaner, which is a good thing for HT.
I moved my wood 4's to the rear surround position, so I still have the woods in the system (which I also like the look of), but the SM in the front can be played much louder without cabinet resonance fuzzing it out.
Let us know what you decide to do! You're going to be very happy with the nOrh stuff.
John G