In my experience, Riv's don't handle heavy front loads well, which I attribute to their high-trail designs. I've read posts that claim otherwise, but for me even a Berthoud-size bag on a front rack, loaded with a moderate-for-its-size weight, isn't as stable as I'd like it to be---especially in a cross-wind. On short tours on my Sam, I carry a large or medium Saddlesack on top of a rear rack and a small Saddlesack on a Mark's rack in front and that works well. If I want to carry more weight in front then I take a different bike, one with lower trail. The ride may be better with the weight lower than I've used, as with panniers, but I haven't tried that.
Dave
Boston/Indy