Very true, and I'm weighing up the Hepco & Becker Easy rack plus top box, or the Ventura system. The Easy rack as it looks less like a top box rack when the box isn't on, and I think it bolts on properly, the Givi seems to use a universal set up which I'm not a fan of as tried to use it on another bike and it seemed to me to be a bit of a bodge job. Which is the same as trying to fit a universal plate onto the Hepco & Becker tube rack.
The top box does give me a bit more peace of mind regarding the security of its contents when I'm not on the bike, and would most times like to have the space and it'll probably be more waterproof. But the Ventura system keeps pulling me in its direction!