They work really well. If you get any of the Aero bags they zip together too. So you could have the one that is in the pic and then another, say smaller one on the back over the rear lights resting on the frame. The upright frame will be between the two bags. Or you could just have the big bag behind you as in the pic and have your lightweight tent, bike cover and sleeping bag on the frame over the lights. Thats how I have it. I've ridden the bike flat out like that. Just don't have too much weight hanging over the back end. Have it over the rear pillion seat or seat cover and the bike will be stable, no problems at all.
You don't have to buy the bags either but the frame is well worth having I think. You can then use your own bags and mix and match things bungyed on the back. The Aero bags are good as they are more rounded for less wind resistance. You don't need the storm bags either. Well I didn't bother with them I just wrapped everything in plastic bags as they are nice and light
My bike with tank cover on but frame removed.