After further testing: no, setBufferedToImage() isn’t good enough once there are components updated frequently enough by timer, so I went back to @pixelpacker’s caching thing and tweaked it a bit. Here’s the latest commit if anyone is interested.
Works OK so far. (Note: I had to set JUCE_DISABLE_COREGRAPHICS_FONT_SMOOTHING=1 for the cached image to look the same as normal rendering.)
Still I think an official solution would be beneficial for quite a lot of end-users - sometimes I can tell an iOS app is built with JUCE just by how meh the knobs feel.