I rarely use Repose in a DF group because, even after telling my party I'll be sleeping mobs someone ends up waking them up, even if I mark them. This is less of a problem in later dungeons as a BLM seems to sleep for speed runs so I can concentrate on other stuff.

I generally prioritise healing, then switch out to DPS (add DoTs and cast Stone II while in Cleric Stance) when things are going smoothly. I haven't done a ton of end-game, but I didn't find Repose useful in any of my level 50 dungeon runs as generally the DPS are AoEing at that point.