Both (dichromates and DAS) have their issues. I believe the clearing bath for DAS is more toxic than that of the dichromates.

But as far as the dichromates, either will do, but I use the Ammonium dichromate(AD) -- which is stronger acting gram-to-gram compared to Potassium dichromate(PD). That is because Ammonium is lighter than Potassium...thus at the same weight of the two compounds, one gets more dichromate using, let's say, one gram of AD than one gram of PD. But once corrected for the difference, they act pretty much t he same.