Here is the answer I received:
The Powermax fuel has been discontinued, The fuel is being discontinued due to low volumes . You might still find some sporting good store from existing stock.
I apologize for the inconvenience.
Coleman Consumer Service
In other words, Powermax fuel is definitely dead. :(
Powermax was the best format out there in terms of gas canisters. It had no threads to cross thread, it had nice aluminum canisters that were very lightweight (a 110g standard canister is heavier than a 300g Powermax canister!), it had a wonderful 35% propane blend in the US (40% propane overseas), and its liquid feed mechanism allowed it to operate down to -4F/-20C according to Coleman (although many users report good results in temperatures down to -10F/-23C).
|A Powermax canister has no threads to cross thread. Just twist and click.|
|The inferno that is the flame of a Coleman Xtreme stove|