The leap second thing is a big issue for a server. OpenNTPD serves the wrong time on the day of the leap second. They don't propagate the leap second flag properly either. It's not correct and doesn't belong in a public server pool IMHO. This issue isn't just theoretical: it was responsible for a lot of the bad time being served by the NTP Pool last week.

You're right that the article I linked argues the leap second isn't a big problem to client machines. I guess I sort of believe it, if you don't care if your client is a second off from true time once every couple of years.