Three words: Autodesk SketchBook Pro. (But you already knew that.)
To be honest, I never thought of Photoshop as a drawing application (though I know some definitely use it that way). Would be nice if they figured out why the brushes are working the way they are though.
yeah, i just don't like the way sketchbook handles. The brushes, due to their darkening overlapping effect, all feel like markers. In photoshop, the brushes handle more like oil paint, which is what I'm used to. also, in photoshop there are transform tools, exposure manipulators, and color balance controls, which really make it easy to toss around a variety of composition schemes in a short time. Sketchbook just doesnt have anything comparable.
So, I realize I'm answering my own post, but just in case anybody else has this issue, this might be helpful. Tonight, I went into task manager (using a galaxy note 10.1...which, in turn, is running on android 4.0.4), touched the RAM manager tab, and pressed the "clear ram" button. i started up photoshop, opened a project that's been pending for some time, and the burn effect was no longer happening. At very least, it was no longer happening at a very noticeable level. So that's my solution. Clear your RAM every time you're about to open Photoshop.