I meant to cast no slur upon front bags and trailers. Great stuff all of it. Just that I am seriously intrigued by what people carry in them. Thanks for the insight, Butterfy. Now I begin to understand! I once took my friend's daughter away camping with us, years ago. She proved to be terrified of going to the toilet outside when wild camping. I think a toilet tent would have been a life saver on that particular trip.
I agree about the weight distribution. Indeed, on my the Holdsworth, and an old Orbit Caraway, my previous touring bikes, when climbing steep hills, the front wheel would tend to lift. When I bought the Roberts, I fitted a front rack, for this reason, intending to use front panniers. However, I found that it has such a long wheelbase, and the wheels are so tough and heavy I guess, this doesn't happen. (I did feel it threatening on Hardknott once, but I had to get off and walk it anyway. My days of climbing stuff over 29 percent loaded are over, I think) I tend to use trains to get to and from touring areas, so I prefer not to struggle with four bags. Two is so much simpler.
Four bags for a weeks shopping? I used to manage the shopping in two Ortliebs. But we are a small family, I guess. And we have milk and most veg delivered.