Pros:
-it works!
Cons:
-The cross-holes are offset on every second row. In my case this meant that some of the units I mounted didn't line up with the holes. Not really a problem as long as you're prepared to do some drilling. The offsets might even be a good thing if you're mounting different gear to me, who knows?
-It sags quite a lot. I mounted 3 FMR compressors (1/3 rack width each), which aren't heavy by any means, but the thing really sagged in the middle. You can fix that to a certain extent by pushing up the middle as you mount it, but it's not perfect.
-Packaging! This thing arrived swathed in polystyrene. That stuff is environmentally heinous and annoying to dispose of. I (kind of) get it with really expensive delicate gear, but a metal rack shelf? Surely in 2024 there's a better solution.