I have to hammer on this a little more. In my above sarcasm I mention what I think is a natural progression: Flames on black backgrounds, flames on light colored backgrounds and then transparent backgrounds. Transparent backgrounds imply compositions. UF is the next step in the progression (aside from scripting). It is the best place to build a flame composition. They can be built in PS but that is only after a flame has been rendered. In UF they are rendered after they are assembled, so the flame color and even the shape can be adjusted before rendering. I would be willing to bet that everyone who learns apo will eventually give UF a try too, and then maybe XD if that style suits them. Apo brings people in and that's great, but it's just the first step. Apo needs to work with UF. It's good for everyone when it does.