If I want to carry 40 kilos of layers pellets, two hefty children or a month's worth of groceries then I attach a trailer to my bike. It adds load capacity but retains the advantages of a bike; I can still filter through traffic, I can still park against railings. Also, a trailer may be eccentric but the Brox is straying into barking.
I use a trailer too. It is supposed to carry up 100kg, but could probably manage much more. I've heard that 150kg has been carried in one that I have.
But it's not great. It topples easily and I need to be very carefull with it. I could easily topple it by hitting a pothole at speed. I have to watch my cornering too.
For the amount of use my trailer gets, then it's the best choice for me. But if I was going to carry bog stuff around regularly, I'd want something less temporary than a trailer.
A trailer is just an add on to use a bike in a way that it wasn't designed for.
This contraption was designed for lugginf stuff around.
It's not for me either, but I still say it rocks.
PS Can I have a go too?