Lately, I picked up one of the fancy OP/TECH straps for my Mamiya RB67. It really really does work. Incredibly well. It was no problem at all carrying the RB67 all around NYC and taking pictures with it.
So, here's what street photography with a medium format camera intended for studio looks like. The guy next to me on the flight back had a Hassleblad 500-series camera and I was amazed at how tiny it looked in comparison to the RB67. It was like a toy!
I found myself taking a lot of vertical orientation pictures, to show the people amongst the giant buildings.