I think the EN 566 is to standard for climbing slings?

http://www.theuiaa.org/upload_area/Safety/Standards/Safety-Standards/UIAA_104_Slings_March_2013.pdf

So it's just 22kn, with some stitching requirements and things like that. Stronger than the required harness strenght of 15kn, but you probably broke something else before hitting 15kn anyways...

I prefer to keep things light and neat. Belts seems to rub against my skin and get things pinched when you wear a harness over the top of it.

I also find the distracting when doing a partner check. Too much stuff. Keep things well organised and neat prevents stupid mistakes of misclipping items to the wrong thing. One of the reasons why I hate those webbing bands that people use to hold up the chalkbag.