Hi Drew,
I wouldn't say I do so many 'environmental portraits' with it (there's one in my portfolio though of child looking out of window/door). But even so I hate having the camera stuck on a tripod for people - I like to be able to move & react.
I also wander about the countryside with it - no problem at all! Lighter than Large Format.
The only time I have it on the tripod is for still life work, or for 'planned' landscapes/docu shots. I can't be bothered with carrying a tripod around on unplanned trips, (i.e. where I haven't got an idea of what I want to take) but maybe I would if I was a 'real' landscape photographer. (I also use 35mm for getting ideas).
But... it's an RZ, not an RB, and that does make a difference - a bit lighter, faster, and the mirror up/film rewind is one movement (two on the RB).
The fact that the 110 lens is relatively fast, plus the fact that the camera is relatively heavy, therefore more stable, makes it very easy to use hand-held/ with available light.
Lots of people say that "don't your arms get tired" - well, no, they don't. A good neck strap balances it very well - of course I don't use a prism! So I'm not lifting it up to my eye at all, which is the part that would be tiring - much easier to hold and balance something at waist level or a bit higher.