The trick here with the water purity is to make sure there is enough agitation to get even development. I have tried with different film to use stand development with uneven results. With semi-stand (2x15 secs) it was noticeable (barely). Comparing the Rodinal to the Blazinal I have noticed slight differences. But that is a whole new ball game that shall not be taken on on this thread. Maybe my next purchase should be distilled water to eliminate some differences. But thanks again to you I can afford a few tests especially with Blazinal for just pennies a roll.
I also noted that Agfa film and Rodinal have been used together with great results for MANY yrs.