While I was at TPF, I picked up a bag of 100 warm white 555 base LEDs from CT, $59. I've always been hesitant to use LEDs in backboxes, but my B/W DMDs were looking kind of dim and sad next to my new POTC. Long story short, I replaced exactly half of the bulbs with LEDs, and left the other half empty. It's perfect! And it cost me less than $15 per game.
As always with LEDs, this pic doesn't do the games justice. I'm very happy with how they turned out. Am I the only one who leaves sockets empty so the translite isn't too bright and washed out?