thanks for the elaborations! Strange that your syrup coloured brown so quickly, in my experience it is a very slow process. After all it's mixed in glycol to retard oxidation, and I believe that Phenidone is still working properly despite the colour shift.
But as you say it might very well be the quality of the TAE, mine is of high purity from Fluka I believe. In my non -scientific test it behaves the same as Xtol 1:1.
Although I now mainly use it now on a a new to me film: Fomapan 100, needs some fine tuning though, contrast is too high, but this film is said to build up contrast easily anyway.
I'll will you follow your results with great interest, keep up the good work and thanks!