Kenko doesn't have coating. And it's not a glass optic - acrylyc lenses.
Actually, chinese CN Scope (review) has coated glass lenses but it's still dark a bit. Darker than Mikko 30x (glass, no coating, a bit less magnification - just a bit).
And still uncomparable with peak 2008-50.

But _good_ lens coating definitely helps And a good optic with no CA(or very low) makes easier to view the edge.