My beloved MX and oft-neglected ZX-M. The usability difference between them is in the eye of the photographer: the MX has one of Pentax's biggest and best pentaprism viewfinders, and the ZX-M has a smaller viewfinder made with mirrors.
The MX was just given some fresh lube on the supply reel shaft to free up the transport, because it's been overlapping frames occasionally. I think I'll be replacing the leatherette soon; it came to me with the original cover falling apart, and I got a kit of cameraleather's navy blue composite material -- which turned out not only to not be blue (it's a dark gray-green in most light) but texturally transparent, showing every bump and crease of the underlying surface. Probably I should try something more conventionally pebbled.