i had all possible versions of fsu cameras, canon p, leica m4 and contax. so from my experience - both kiev II and kiev 4 and super smooth and easy to focus. my kievs are much more silent than any of the camers i had. if you dont mind the small viewfinder you will be super happy with any of kievs. the later kiev 4
versions with black plastic rewind button are slightly louder but i never saw any problems with them.
many people will tell you that QC was bad in SSSR but the problem is not in QC but in conditions cameras were stored in. when someone has leica he cuddles it and all and russian cameras were found mostly in flea markets and kept often in really bad conditions last 30 years or totlaly unused. so if you buy from anyone who was at least using camera a bit - you wont feel any difference between contax,leica or kiev or any other fsu camera in general.