I had the Addit on my commuter/tourer for a few years. Sturdy rack with round stays, as cyccommute notes. Before this I had an old Blackburn rack with flat stays and they definitely left something to be desired. The Addit works well with Ortlieb bags, which are sturdier than the Racktime bags, and don’t have quite the same price premium Tubus has over Racktime. I purchased a Racktime top bag that clips in the mount, but found it to be not well suited to my commuting needs. Too tall and not waterproof or as sturdy in construction as the Ortlieb bags. Clipping in and out was a nice feature, but not as useful as I thought it would be. About the only time it was useful was for small family outings to tote along drinks and snacks, that sort of thing. That’s my two cents worth.
Pretty sure I ordered the Addit from one of the German bike retailers, as I could not find it in the US at the time. The bags, oddly enough did pop up in the US, often on Sierra Trading post (also a good source for Ortlieb bags).