I have the Lezyne EX. I use the folding panniers on a daily basis. I keep my lunch bag in one side and the other side I have a change of clothes and some work items. In the upper trunk I keep my rain gear, extra tube, and pump. There is a rear flap to keep a small tool kit and a side flap to store a u-lock.
The bag has pros and cons. It's well thought out for storage and has plenty of room. It even has a shoulder strap (removable) to easily carry it with. The attachment/removal is pretty easy. Takes me about ten seconds with a couple of hooks and clips. I don't know how it compares to an Ortelib style attachment system, as I've never used one. The biggest drawback to this bag is the pannier attachment hooks. Hard metal hooks that clip onto the bottom portion on rack (i image most foldable panniers use something similar). They work well, but if they are not tensioned enough they can slide off. If that happens, then you have a hard steel hook swinging next to your spokes. I screwed up one day and destroyed my rear wheel. For all of the great things about this bag, that last point made we want to go with full panniers.