Regardless of how you quote or emphasise your text, it doesn't mean you'll beat me into submission
While I agree the effect from 130->150mm will not be night and day, it will still be significant...who doesn't want a bigger scope?!?
Btw, surface brightness - by definition - is dependent on the
surface area of the objective, not the diameter of the aperture. As a result, the increase in light is not 150/130 = 1.15, but (150/130)^2 = 1.33...