Tobus: I don't wear a belt when I wear a waistcoat, but I think the look is somewhat incomplete when worn with just a shirt. Your brown belt and buckle have a nice look to them as does the ferguson britt sporran....
Actually, my wife and I built that sporran. FB sporrans are much better quality than that. My wife made (and hand-tooled) the belt. That buckle design is available through various internet vendors, and I chose it for the same reasons you stated. I like the 'complete' look of a belt when not wearing a waistcoat, but I don't want a flashy waistplate for daywear. This seemed like a good compromise, since it's a brushed/antiqued finish and isn't rectangular. The shape of it seems to tone down the visual impact a bit.