There is absolutely nothing wrong with using a Tessar Rolleiflex, or a Rolleicord with a Schneider Xenar (there are no Tessars in Rolleicord cameras!). I would advise against a Zeiss Triotar and I would certainly go for a coated variant.

If used wide open, a Planar is sharper in the corners but that's about all the difference. Actually, I would consider the differences between the cameras that use the different lenses more important than the lens. Alll in all, a well maintained MX-EVS (with a bright screen) may provide much more photographic fun than a worn out 2,8 F...