As far as HOV lanes are concerned, IMO they should use the OUTSIDE (right) lane so there's no confusion about where the passing lane is. That's one thing that Kelowna did right a couple of years ago when they instituted HOV lanes, much better than the left-sided HOV lanes in Vancouver which scare the bejeezus out of me.
If I was legally driving in a left-sided HOV lane and someone was pushing me to let them pass, I'd stay put and let THEM move over to the passing lane. Changing lanes to the right with some speed-crazed jackass on your tail is asking for trouble.