The support frame for the top case does not look extremely solid from the photo's. Also the bit leaning on the plastic fender seems like it could cause the plastic to crack after hitting a bump.
How does it feel in real life, is it rock solid? How much weight can you carry, could it hold a laptop and lock (say about 10kg total weight) and survive a bump?
Yeah, it certainly did seem that way when I first installed it. But the bars are held by two sets of bolts, one horizontal for the seat mount and one vertical in front of that, so there's some vertical firmness.
I can't tell whether fatigue on the tail section will be a problem in the future, but it's not bearing a lot of weight and there's a rubbery cover over the metal bit that sits on the tail. So it seems fine to me, if not an ideal design.
Regarding capacity, so far, I've carried groceries or a helmet and laptop, and it feels solid and within the specification. I do have the dual sport suspension but I live in Seattle with its potholes particularly on the gravel alley leading to my driveway.