Mike, how is that rangefinder in practical use? It strikes me as a rather outrageous, excessive, and cumbersome demonstration piece by F&H ("Look! We can make anything work") and probably harder than focusing the 'flex the old-fashioned way. But I've never handled one.
Am I correct also that once you've installed the thing, there's no case or cover for it, and you're putting the camera away in your bag with that central glass piece exposed? (And you wouldn't want to uninstall and reinstall with every stop along a walk or trek, because you'd have to redo the calibration each time?)
--Dave