Frank, Yes I used the High setting. There was a good amount of steam that comes off of it when you open the lid though. When I do it next time I'm going to leave it on 8 hours on High, unplug it and let it cool for a few hours then take them out. That way you don't have to accidentally breath any of the steam.
Not sure about hardcoated pipes. They were never difficult to clean for me. Read the whole thread someone said you could do it just not too long or it would start to remove the coating. It was in an earlier post