I bought Saddlemen throwovers for mine. I tried leaving them as throwovers for a while, but with the yokes over the back fender and the ties holding the bags to the supports, I was a long way from the clean, permanent look I wanted. And since I use the bags every time I ride, or near enough, I didn't really see the point in being able to take them off.
So I got a couple fender washers, grabbed the ol' C3, and hardmounted 'em. I don't regret it. While it's true you can't just pack stuff in the bags then take 'em off the bike while traveling, they do make zippered inserts for them. I haven't tried them, but they're on my list of potential purchases.
2011 Victory Cross Roads, crimson red
"There is only one God, and His name is Death. And there is only one thing we say to Death: 'not today.'"