I own (in order by year of manufacture):
- Ricoh Singlex TLS
- Pentax KX
- Ricoh XR-2s
- Ricoh XR7
- Pentax Super Program
All have their plus/minus points and I don't know if I could offer a blanket statement regarding quality/ruggedness/dependability by brand. I can offer a few points regarding each body, though
Singlex: Very ruggedly built, especially the shutter (legendary Copal "square" vertical). Larger and heavier than a Spotmatic (its much more expensive contemporary). I have had mine for about 15 years with no maintenance beyond seals and yes, the meter still works and the shutter is still accurate.
KX: Solidly built with a form factor and handling very similar to a Spotmatic. In my opinion, the KX is probably the finest and best-featured non-AE K-mount SLR ever made. That being said, the flash sync is limited to 1/60s due to the horizontal run shutter and the ISO set mechanism is flimsy. I will never sell mine.
XR-2s: Almost identical in dimensions to the KX with very similar control layout. It matches the KX for every feature except MLU, but adds Av mode and 1/125s flash sync. Lighter than the KX, but with more robust Copal shutter. The XR-2s is resin clad over a metal (non-cast) carriage. Great value considering the price comparison to a KX. Truth be known, I reach for this one over the KX, but mostly because I don't want to risk cosmetic damage to the KX.
XR7: Small and light and very rugged due to resin-clad cast/cnc aluminum carriage. Bright, full information viewfinder. The build "feel" is somewhat below that of the Super Program, but is made up for by much better control layout, usability and handling. It also has AE lock. Also great value and much preferable to an ME Super IMHO. In regards to the ruggedness claim...I bought my first XR7 new and carried it thousands of miles slung on the outside of my external frame backpack. Yep, banging and swinging along. When it finally died after 25 years of heavy use, it was due to being mounted to a defective lens that resulted in a munged aperture coupling. That kind of insult would have been fatal for most cameras. The replacement XR7 was purchased for $25 with two zooms from Goodwill a couple of years ago. I really should pick up another for when it dies (!).
Super Program: Tiny and light with a high quality feel throughout. Great handling. Resin clad over metal body with great feature set. Best feature set of the A-series Pentax cameras. No AE lock. Control layout and usage sucks. LCD display in viewfinder hard to use in dim light (so what else is new?). True TTL flash. Despite its good points, this is one K-mount SLR that I may well sell. The XR7 is a much nicer camera for shooting.
Regarding the KR-Super II...If you need a camera for "beater" duty, it is pretty hard to lose at $25 including lens, as long as the features all work and the battery compartment is clean. The Rikenon 50/1.7 is OK, but the Pentax-M is much better. That being said, don't sell the KX. When the KR-Super II dies, it is a throwaway camera. For all practical purposes it cannot be repaired. OTOH, all of the systems on the KX are repairable and serviceable and it is capable of lasting a lifetime with periodic maintenance.
Buy the Ricoh and keep the KX.
Steve
(For those that have an interest, there are photos of all of the above cameras and a few more
HERE. Oops...just noticed that the KX is not represented! Will have to fix that...)