1x3 presets (which have real-time correct preview) do work with HDMI output, but only in 1080i output and in Full Canon preview (toggle between Small and Full Canon preview by pressing Info button while in 1080i output), the quality is good enough and of course it's better than camera LCD, but it suffer from aliasing and moire in LiveView (this also happens on LCD).
-I didn't have corrupted frames with 1x3 presets and 1080i HDMI (tested on 700D).
As far as I know, Danne did implement HDMI support for 1x3 presets for EOS M but he didn't test it, you need to make some tests (e.g try it on any TV with 1080i output) then feedback.