There is no such think like a Rollei that is unpro ;-) I think all the TLRs are pro. Even the Rolleicord. SL66 was also a highly professional camera (but not as resilient). Rollei 6000 is a professional system, as is the Hy6. I have no experience with the Rollei 35mm cameras though, but I think all the 6x6 Rolleis are very dependable and durable as long as they are treated accordingly and serviced from time to time. When it really comes to abuse, I think the TLRs can take the most. I once have seen a 2,8F listed on Ebay that looked really beaten, but was fully functional. It went for only 300 bucks, unfortunately I missed it.