I've used them. They require some labor-intensive prep work, and there are some markers that seem to take a more permanent liking to the surface, but otherwise not bad (unless you leave that To Do list up for two months).
Think of it as a giant shared 3rd monitor. Would you buy monitors that ghosted if your programmers typed the "wrong" letter combinations?
No, but that's not analogous to my experience.
Given that my company had more time than money, the DIY boards worked really well for the time, cost, and effort, and the value we got out of them.
Sometimes good enough really is good enough.
All you need is a 3$ bottle of white board cleaning spray
...which works less each time around, and stinks, and uses paper towels, and takes a few minutes of wiping each time you want to get (close to) clean again.
Top-quality surfaces wipe back to bright white with a single swipe or two of the dry-eraser, even if the text has been up for weeks. They're worth it for many offices.
Also, have you used any of those $10 sheets of melamine? They ghost up after a couple of months of use...