Reading Rivendell's catalogue, it seems that a heavier load (in the rider or loaded touring) needs a bigger tire. Could a larger tire (larger than 700cx23!) help with periodic broken spokes?
My friend is about 250lbs, very strong legs, and keeps breaking spokes on his Rush Hour. I've suggested larger tires (don't know how big that bike will accept). Or does he need to get better spokes and/or rims?