I walk around with my RB67's as well. If you want to try something really different for nature or landscape, consider a medium format folder like a Zeiss Nettar.
I won't denounce anyone that insists the RB67 is a "studio camera", to each their own. But, I regularly sling mine around my neck and monkey about on the fore-deck of sailboats under sail.
Also, I don't know how common they are but there is a 6x4.5 back for the RB67 as well. I have one that needs light seals but don't feel a pressing need for it.