I use the regular akadama in nearly everything (mixed with other soil materials). I have found that the high fired stuff actually seemed to break down faster here in Florida than the regular stuff. I know what you are thinking and it did not make sense to me either but I tried it twice and the results were the same both times. Side by side with same type tree and same watering methods.
Even if it did not break down like that I would not use it - the regular stuff is a bit less expensive.