I have wire saws from BCB and Coghlan´s. The saws need to be handled and stored properly. If they get kinks or are bent excessively during the cut, there are destroyed pretty quickly. When you apply little pressure and pull straight, they can be used for a long time. I´ve used my BCB saw to fit wood boards for a colleagues kitchen and to cut tree limbs. The cuts where pretty precise and the saw doesn´t show any signs of wear.
OTOH I´ve seen one saw destroyed after cutting half way through a half inch tree limb. The guy who destroyed it applied a lot of pressure which resulted in a small bending radius. The saw got too hot and broke at a kink. The forum rules do not allow to quote his opinion on wire saws.
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If it isn´t broken, it doesn´t have enough features yet.