Got the Kriega bags they are very good, but access is a pain during a day of riding when you might want to retrive something.
Found the Ogio stealth (or the Dainese D Bag if you want to pay more the the branding!) and it fits very well on the pillion seat. You can get a good 20-23 litres in it, but as Chas implies mounting the bike will become more of a challenge!
Stuck on a rock off the coast of France