David,
I use an Opemus enlarger for 35mm and 6x5.4. Since I use a colour head, I keep the 6x6 mixing box on at all times. No need to change condensers unless you want to make ridiculously large prints from ridiculously small pieces of film.

But if someone has a spare pair of 240mm condensers for a Durst 138S, I'd be happy to give them a new home in Norway.