I agree with Bruce and Brian. Plaster is slightly better at thermal insulation, vastly better at sound insulation, and the right material for a 1915 house.
Almost any plaster wall can be repaired, even if at first it seems absolutely hopeless. Brian's site at WWW.ORNAMENTALPLASTER.COM has got a lot of tips on plaster repairs, both big an small, as well as a lot of history and general information. Thanks Brian!