So far our experience has been with Rift (DK1, DK2, CV1) and Gear VR using Unity across 2 games we have ported to VR (Into the Dead and Breakneck). We have Vive kits on the way.
Unity has been pretty good for our development in general in terms of rapid development, flexibility, and portability. Though we've had issues with frame rate and Unity isn't the easiest engine to optimize. They do have stability and performance being a focus of upcoming versions, so hopefully that becomes less of an issue.
In practical terms, the logistics of putting headsets on and off isn't really a problem, at least not to the point where I'd consider it a burden. The real issue is VR fatigue and nausea, especially early on in the development cycle where you are prototyping camera and controls, and there are lots of bugs. Very easy for people to get sick very fast, and have that last with them for hours. We've had to send people home for the day several times.
Would suggest a way to manage things would be frequent breaks including getting outside for fresh air and to reorient yourself, and keeping cold drinking water on hand.