I have a Challenger (Eaton Cutler Hammer) 200A load center in my home with 30 1" spaces (BR style breakers). I have used up all available spaces and have a need for a few more circuits. The panel is located in the attached garage which is currently unfinished. I'm about to finish off the garage and have to decide whether I should change out the panel for a 40 space unit (much easier to do now before the drywall is in) or to use the "Space Saver" twin pole breakers. I have never used the twin pole (2 breaker circuits in a 1" space) breakers. What are the pros and cons? The twin poles will give me enough circuits now and in the foreseeable future, but of course the 40 space unit will give me even more room for future expansion if I need it. What should I do?