I have those Transits and use them every day on my commuter. I really load 'em up. A lot. Laptop in it's bag, school papers and books, clothes and food.
I toss a bungee cord on for the laptop just because I'm a nervous about it. But they've held up well and work well. The reflector really reflects too.

Note that I had to hang them on the back part of the rack to get foot clearance.