I'd have to contend that using a paramender (which could of course apply to any make of TLR) would be the 'best solution' though. Compensating viewfinders, or even prisms on the viewing lens, still leave you looking at the subject and judging the composition and focussing from the wrong angle. A paramender, if it's accurately configured, will allow you to compose and focus from exactly the right place, and then quickly and precisely move the taking lens into position for the shot.
<cheap dig> Of course, these things admittedly matter less at the sort of distances that a Rolleiflex with CU lenses can manage - with a Mamiyaflex one is able to get into the sort of magnification realms where precision matters more. </cheap dig> ;-)