Steve, lenses of the same focal length, whether collapsible or rigid, will behave in the same way with any given film format and for the same circle of confusion. Maybe lenses exist with distance scales marked inaccurately, but I have yet to see one or hear of one. The same goes for depth of field markings. What it boils down to is two things: careful handling to avoid accidents (Roland) and possible difficulty seeing what you want on the scales (Richard).
Thanks, Ash: it is sweet stuff.