The R6 and R6.2 had a body with the XD-11 size and shape, but the interior was all mechanical except for the light meter. It was only a bit larger and heavier than an M6. Minolta never built anything like the R6, even though it has the XD-11 shape on the outside.
Given the electronic/mechanical concerns and size difference, I wouldn't consider the R8/9 an equivalent to the R6/6.2. (That's not to say that both aren't great cameras, just very different design concepts.) I took it that battery dependence was the issue, not reliability per se. Maybe that's why Salgado used them in far flung places.