Richard,
What type of machine actually made the recordings used for the test ? I would think that the small variations in the original record characteristics might lead to more or less tracking errors in the Dolby A decoders, when compounded by the playback characteristics of the different machines. Why use Dolby tapes at all ? Also, did you try 30 ips as well..?
Just curious as to your reasoning on these points, I'm not criticizing....
Scott