Using the HD500 Looper in a live setting is cumbersome due to the number of footstomps required to engage/disengage the looper while switching patches for different tones.
For instance, a common situation is to lay down a chord sequence for the verse portion of a song to be used as a backing track when the lead solo, using a different preset, comes along, then segue smoothly back into playing a verse or bridge live. Laying down the original loop is no problem - you engage Looper mode, then use the footswitches to start and stop recording the loop. At that point you probably aren't at the point in the song for your lead solo so you stop the loop playback. Now when the solo comes along you need to almost simultaneously start the loop playback while also switching presets for the solo. Some fancy footwork is required to achieve that and maintain tempo. If you manage that successfully, you still have to disengage the loop playback when the solo ends and also switch presets back to the original - also while maintaining tempo.
Try it. It requires both careful planning to start/stop recording your loop at the 'right' instants (which may not be on the beat if you want to allow time for patch switching) and also some extremely fast and accurate footwork in the stomp sequences. I haven't been able to master it while keeping my playing tempo.
Life is what happens to you while you're busy making other plans.
.... John Lennon