Having owned both, I can empirically claim that the 3.5 Solinar is every bit as competent as the Planar of the same era on the Rolleiflex (and at 1/3 the price). Both fine pieces of German glass.
“The day I understood everything, was the day I stopped trying to figure everything out. The day I knew peace was the day I let everything go.”
― C. JoyBell C.