There is a difference between maximum structural cruising speed, Vno (start of the yellow arc) and maximum maneuvering speed Va (often not marked on ASI). For the Beech 23 Vno is 136knots and Va is 118 knots IAS, there is no mention of wieght in the POH, I guess they worked it out on the worst case and kept it simple. For the RV6a Vno is 156knots and Va is 117knots IAS again no mention of wieght. Most thinking pilots will err on the side of caution.