Ok i`ll chip with my experience of FSU. I have 4, all via E-bay. All work just fine. Zorki 4 is another good option with industar 61 lens. Kiev 4 is a fun quirky camera, a bit big and it takes some getting used to the ergonomics. Fed 4/5 are also quite bulky. Zorki 6 has a hinged back [ the others have fully removable back] and it also has a very wide rangefinder base. Fed 2 has wide base and is considered one of the best from FSU , however perhaps all the good ones are in use.There are so many variables with these cameras, for instance a pre 1964 zorki 4 will have engraved speed settings, post 64 they are embosed and wear. Earlier Jupiter 8 lens[1950`s] are better than later, post 74 Kiev is not well made- and so on.
All of mine are the complete opposite to what people say are the optimum and i have not had a problem with any...though it is only a matter of time..:-) They are fun and do what they were made to do well, the lens are overall very good. My pick from this lot? probably Zorki 4 with ID 61.If you want an idea of what the models look like and more info