As mentioned above by Nick they are extremely heavy. Having lugged one around the North Cornish coast, would never have another for landscape use.
However for Architecture where you can park nearby they are OK.
I found that I needed a 5 x 4 for better rendition of buildings I was photographing at the time and P/Xed it for an Ebony 45SU which even with four lenses was a lot easier to carry around. I am not sure when these were discontinued but it would probably be worth checking on servicing availability.
C