I have two Beseler 4x5 enlargers in my 8' x 9' space. One is set up with the 6x7 mixing chamber in the 45S head, and the other has the 4x5 mixing chamber. The 11x14 masking frame usually lives on the medium format setup, and the 20x16 frame on the 4x5. This sames a little time in locating the correct lens and carrier, especially if I am working on multiple formats. Since the 45s heads can be exchanged, or a condenser head swapped in, I have enough redundancy.
Though I still have a Durst M605 and F30 broken down and in storage!