Detlof, glad to hear you are giving the Record Research fluid a workout. There are a couple of issues with testing these cleaners that should be considered. First, the fluid I sent you was part one of a two part solution. It is the heavy duty version, developed as a replacement for the (EPA) banned "First" which was a Freon based product. A second cleaning should be done with Record Research Vinyl Wash, the more dilute every day cleaner.
Do I understand from your post that you washed with the Record Research and then washed again with Nitty Gritty? If so, you have not heard the Record Research properly. You should wash off the Nitty Gritty with the RR and do no additional rinse for your next test. The only bottle of Vinyl Wash I had on hand was the 32 oz. size, and no small "clean" containers to make up a sample.
I will ask RR if they will send me sample size versions of Vinyl Wash, or mail me some clean sample bottles, and I will pour you enough for the test. I just wanted you to have the chance to hear this for yourself, and sent what I had on hand. Judging from your well written post, you appear to be (mostly) favorably impressed. Perhaps the follow up rinse with this additional RR product will provide the magic you are after.
Doug, Maicomike, Slawney, Deshapiro, and others, are you interested in trying this too? If so, I should know in advance so I can ask for some extras when I contract RR. Hopefully all of you will follow up with your own results if you wish to become involved.