Lovely camera. I've been using a 501CM for many years.
Used Hassy bodies, 80mm lenses and backs are widely available at good prices. A lot of wedding photographers have switched to digital and this has resulted in a lot of Hassy equipment on the used camera market.
New Hassy lenses, in general, are grossly over priced, as are new Hassy accessories.
The available range of 120 roll film emulsions is much greater than 220. IMO multiple 120 backs are a more flexible approach than 220's. If I was doing wedding photography, I might change my mind.