I'm going to be the dissenting voice here. I've had and used extensively an R3A and R3M, and I've got a Hexar RF. While the Hexar is a very nicely-designed camera, they cut corners in one crucial area - the rangefinder mechanism. To put it bluntly, they cheaped out when they put it together, and it is prone to getting knocked out of alignment or breaking. And because Konica no longer exists as a company, getting replacement parts is next to impossible. I bought my Hexar used and it arrived damaged (it simply would not focus properly), and although I managed to get it fixed (by Precision Camera), it's still not great, partly because they couldn't get new parts for it.
I'm not alone in my feelings about the Hexar. Tom Abrahamsson, who knows a thing or two about rangefinder cameras, claimed he could knock his Hexar rangefinder out of alignment by putting the camera in his bag the wrong way. An exaggeration, perhaps, but I know that he ended up adjusting the rangefinder then loc-tighting it into place to hold it there.
Don't get me wrong - I would love to love the Hexar. I really like the AE, the magnification of the VF, the power winding, and the titanium body, but the rangefinder mechanism is its achilles heel, IMHO.
On the other hand, I have dragged my R3A and R3M through Cambodia, Sri Lanka, Thailand, Malaysia and Borneo and never had a problem with anything.