Ultra Make a Great PFD that we have been using.
Designed for paddling, it sits very high around the chest. Harnesses do not get in the way.
Be careful of Mystic, and other "impact vests", they are not PFD rated.
If you would like more info on were to get one , PM us. Ultra are keen to get into kiteboarding and will price there product well to do so.
http://www.ultrapfd.com.au/default.asp?PageID=62&n=Pinnacle+Series+II