First, my Tubus Fly rack weighs 12 ounces. I much prefer a Bagman support with my Barley, and that also weighs about 12 ounces.
Second, you need to get a handle on how much space you need. The barley is great, but it's not much use for groceries.
Third, lower is better if you're talking some weight. You might want to consider getting a Tubus Fly and use your current panniers.
I have had mine for several years, it's tough.
http://www.lickbike.com/productpage....=%273590-00%27