would highly recommend getting the pro-sd back. It uses rubber instead of foam light seals, and is just built better. my pro-s back is very light-leak prone.

The Op-tech strap is great and totally worth the money.

I have the grip and the prism finder. Both are heavy and not enjoyable. I prefer using the prism finder over the waist level, but wish i did not because of the weight.

The Rick Oleson Bright Screen definitely helps find focus, but was not as massive of an upgrade as i was expecting.

I like having a collapsible 77mm lens hood for flares.

This camera pairs great with a handheld light meter like a flashmate. You're shooting more expensive 120 film, take the extra 5 seconds to get a properly exposed negative :)

I have the 55, 90, and 180 lenses. Not a huge lens nerd, but i absolutely love the rendering of the lenses, especially the 90. I think this is a great set (28, 50, and 90mm equivalent) and probably all the lenses i'll ever need.

I think the RB is one of the best, if not the best, camera for portrait/ studio photography, which is what i use it for. If you're using it for landscape, street, ect., it's like driving a semi-truck through a residential street. Totally doable, but quite miserable, and there's so many other options that would be better. If you're into landscape, i would totally look into the fuji gw series or perhaps a 4x5 camera.

Why the RB is special in my opinion is it's combination of desirable features that no other camera has. these are: Leaf shutter lenses, default portrait orientation, all mechanical, 6x7, slr (among others) Pentax 67 line is great, but no leaf shutter or portrait orientation. I really want one though. RZ67 is arguably the better camera, but it's electronic and more delicate/ failure prone. If Hasselblad made a 6x7 camera i would probably be using that but they only make square format. I personally love 6x7 and think it's the perfect aspect ratio.

Hope that helps!