I prefer black with black but if you're confortable wearing brown with black and if your circuit rules allow it, it's okay too. Just do what makes you feel confident and happy. :)
Im not the biggest fan of it. If you can get matching colors I would do that.
I would avoid it. I grew up with a very traditional riding dress code and still like to see black belts with black boots.
I do it all the time! I prefer the look of a brown belt with my tan breeches :)
If you don't wear any other color, I think it can be good, that's simple colors, I mean it would be different if it was red boots and yellow belt! So I don't think it would be unfashionable but don't wear an other different color! :)
I meant to look for a new black belt (my old one is a bit too big), but I ended up finding a green and brown belt I like and I'm trying to decide if it would be a weird/totally unfashionable for me to mix a brown belt and black boots (especially in competitions), or if that is normal.