I own a koowheel and have used it hard, it's still going despite my abuse, I'm personally pretty impressed with it for a low end e-sk8.
Only thing I've modified was softer bushes for carving
Has anyone checked out these Chinese ones? They look a lot more legit than the ones from a few years ago. The build quality looks a lot better.
https://www.youtube.com/watch?v=8yRNB5FGekM