To flesh this out- the screens on Rolleiflex TLRs with removable hoods are all the same size. Including the T, and also the Rolleicord Vb. The screens on Rolleiflex TLRs without removable hoods are all the same size (back to the Automats, at least) but not the same size as on removable hood models.
I don't know about the FX and GX models. I also don't know about the screens on the Rolleiflex SLRs except that they are very high quality screens- bright, snappy focus, etc.