I've couple of Topeak beam racks. Great idea in principle but always find that when loaded they eventually they slip sideways when you are riding which means they make contact with the rear wheel meaning you have to stop and re-secure from time to time. Have used one on my Brompton with varying degrees of success. A few years ago when I was looking for a new rear rack I looked at the Topeak Tourist DX iirc, the top range one. Got it home and tried it against my bike but it was just far too high so returned it to
Halfords. I didn't think the bracing was that great on them but never used one for real so might be wrong. Instead I bought a Madison Summit rear rack which has proved to be a fantastic very strong, very stiff with good bracing, durable and light rear rack. So much so that I bought replacements for my other bikes. So much better than the crappy Blackburn racks that I had previously which all broke.
Again Topeak's idea of collapsible side panniers seems good in principle but I wonder how long before they start letting in a lot of water? Plus they seem a bit of a faff. Ortlieb panniers are far better.