I only ran clipless pedals on an upright bike for a few weeks. Practiced enough with the bike on my trainer to avoid tipping. Took them off not long after because of the knee pain they caused.

I now run clipless pedals on my recumbent trike - helps keep the feet up off the ground, thus avoiding leg suck.

The best part about clipless pedals on the trike? I can come to a stop and not have to unclip or worry about falling over. On my uprights I continue to run bare pedals.