i have found in the past that the black and white leaflets have worked better than coloured glossy leaflets for me anyway. i dont know why, maybe because
the black and white leaflets look like the custys would get a cheaper quote because of the quality of the leaflets, maybe becuase they show your not a big firm , just a one man show so therefore keeping the price down. try it and see, i bet you get a better responce, a good idea is to re-deliver your leaflets every month just to remind them your still about and to remind them to get them off their ass and lift the phone, thats if you dont want to door knock like me that is.
kind regards
paul