In these calculations the 1.5 figure represents the Factor of Safety. The 1.15 figure is the Fitting Factor. Replacement of these wires is strongly recommended. This would also require examination of the associated compression tubes and the tube end fittings to which the wires are attached plus examination of the bearing of the fitting bolts against the wooden spars. It is recommended that Fly Baby owners contact the designer regarding possible changes to the wing structure to meet current design criteria.
Peace of mind is important when flying a homebuilt airplane.
Upgrading the internal bracing wire and turnbuckles on a Fly Baby has trivial impact on cost and weight. If I were building a Fly Baby, I'd do the upgrades the Canadian EAA recommends. As I bought my Fly Baby instead of building it myself, I'm not sure whether it has these modifications. A number of people have flown mild aerobatics with their Fly Babies with no problems. Anyway, whatever the actual load factor, this doesn't seem to be causing any problems in the field.