My 1957 J-3 gives me the results I expected from this lens. It was shimmed by a fellow RFF member at some point. Of course its a fast Sonnar, but I only need to remember to "lean in" about 5cm when shooting wide open and close.
My 1960's J-8 is a perfectly fine lens but not remarkable in any way. Consequently, I fine myself passing over the lens in favor of one of the many (too many?) other 50's in my lens closet. I think the J-8 makes a good lens for an economy setup, or for those times when you anticipate potential risk to your equipment -- in that case the J-8 is nearly ideal because its performance is rather good. Same comments apply to my 1970's J-8. I never had one of the more recent black ones. Some people say they're quite good (as opposed to the recent black J-3).