Good questions. You do not, and should not, combine ephedra with Phenyltropic PPA. Phenyltropic PPA contains Nor-ephedrine, which is similar to ephedrine. Nor-ephedrine promotes better appetite control and is less speedy.
Drug based supplements tend to be more potent and also tend to be more true to label claim (read more pure), since you have to have a DEA license to work with drugs, but not herbals.
This may all be moot, because as I mentioned, the FDA hates Phenyltropic PPA, so in the future, herbals may be all you can get.