I've used the Australian version of the Cascade-Platinum Action-Pacs (Albeit, with Phosphates), and if that's any guide on the performance of the Phosphate-Free version, its damn good!
Otherwise, you might consider Bubble-Bandit, although I still haven't found out if its Chlorine Based, or Enzymes + Oxygen Bleach.
Check up the MSDS before you splurge.
Other suggestions include the "new" Institutional Cascade, that is Cascade Professional - Fryer Boil-Out. Its the same formula, if you compare the MSDS information between the old and new.
You might also try the Chlorinated Hytron detergent, another institutional product that comes in Pails (Up to 50lb, from 25, 10 and 5) I think as well as sachets.
I have some American friends who have gotten Cascade powder... Their plastic cups have a weird haze to them and feel really odd. Their dishwasher is full of streaking and water deposits now. Other plates and stuff aren't getting clean.
Detergent dosage is adequate, and the heavy cycle being used. Not a good indicator - and this is with softened water at their house.