@andrewilley i am slightly puzzled by user insistance on core app functionality and the apparent willingness to forego additional features if they are not in the main app. In android, apps are "running" most of the time and switching is just 2 taps, probably the same "effort" as selecting this option in Poweramp should it be available. The notion you would need to exit Poweramp is false. As you know my app creates playlists directly in Poweramp so you could see npm as an extension rather than a separate app. By the same token, user do not use Poweramp as their main mp3 editor, they use an external app which does the job a little better.
Although these npm smart playlists do not react and update on changes by themselves, i have recently provided an option to update them so one click will suffice to update all your smart playlists. (No doubt this process could be triggered by some event)