I Just mounted a Prime Designs Alurack and ladder on my 2020 high / extended last weekend. The build quality is kinda low, things feel kinda off, holes don't line up, directions were shite ... but ... the price was WAY right compared to the other options (no sprinter tax), the width is better than the other options (9+ inches), the movable cross members are nice and allow for flexibility in spacing. My wife and I were able to do the install by ourselves in our front yard with no extra-special equipment.
I prefer the look of a wide rack on top rather than what I call the narrow "cherry on top" look. If you are planning on using your rack to haul kayaks, ski gear, sup's, boxes you need room to operate.
I mounted my Thule box tonight and it's clear I'm going to have plenty of room to mount a larger residential solar panel (up front), a spot for a Maxxfan (just behind), the Thule box and at least 2 whitewater kayaks or sups (using stackers) in the back with a small platform to stand on in between, no problem.
I ordered an extra 2 heavy duty cross members and added them to what normally comes with the rack (3 heavy duty, 3 lighter duty i think) ... but now I'm thinking of ordering 2 more and making all the cross members in the back half heavy duty versions (where kayaks, box and humans go). They are quite a bit more stiff. Highly recommended.
I'm vain enough to have spray painted the side rails and mounting hardware black in an effort to simulate the $5000 price tag racks ... and it looks slick as snot right now ... not sure it will last. The shiny aluminum doesn't work for me. If my spray paint job flakes away I might have a professional giv'er. The rear ladder came in anodized black and looks way better. Clearly, Prime Designs should offer the Alurack in black and cater just a bit more to the van enthusiast. They are leaving money on the table.
As for the weight capacity: I've been whitewater kayaking for a long time now. If you kayak you know and have born witness to the ridiculous amounts of kayaks / weight strapped to "racks" and driven up and down "roads" with nary a hiccup. I've personally strapped several hundreds of pounds of gear on very janky racks. Informed with that experience, I can tell you that this rack will carry just fine.