Thought I'd share my modified Vario rack. I love the rack, it's convenient to strap a backpack onto, but I found that I was easily exceeding the maximum load. Carrying 20+ pounds on the rack resulted in the spine of the rack bending and my backpack would make contact with the rear wheel. As an experiment, I took some scrap 1/4" aluminum and reinforced the spine. I bent it to conform to the rack and it provided a convenient place to mount my Gopro and a tail light.
I've been riding with this setup for the past few months and it's been holding up. I think the maximum I've loaded it with is a little under 30 pounds. I'm amazed the plastic seat post bracket can support the weight.