Bungee hook systems work pretty well with the Jandd expedition style racks... anything with that bent stay can be finangled so the elastic is looped the whole way around the rack stay and the hook attaches to a D ring on the pannier. This is very secure and works well. It's also a pain to get off the bike.

The Ortleib system works better with a Blackburn style 3 stay rack. The straight stays do not allow for the looped elastic, but the multiple hooks do fine. IIRC the Ortleib system will work ok with the bent stay racks too, so it's a bit more flexible. (hopefully testing won't come up, since atm that would involve me riding a bike that's a good 2 sizes too big)