There are 2 types of Murphy Beds I have seen in RV's...those built-in to a couch (common in Class B's) and full wall cabinets.
The mattress in a Muphy unit will always be better than any other options, 'cuz it does not have to fold up. The problem is lost space due to the wall cabinet.
The big upside is all you have to do is turn up the sheets and close the bed...then that room can have a completely different use.
The couch mounted versions have eliminated some of the space loss, but then the pivot point of the bed deck is high, up on the top of the couch seat base.
I think they are rare because not many customers ask for them, instead expecting sofa sleepers for the additional berthing for guests with a regular bed for the bedroom.
As with most everything in RV's, it is all about what YOU want. Murphy Beds are great...just not that common.
Kim and Steve, Mustang LCDR (Ret), '07 Damon Outlaw #1193
I have seen gross intolerance shown in support of tolerance, Samuel Coleridge
WE LOVE OUR OUTLAW RV