I wear my stillwater belt with my stillwater out of necessity. I bought the kilt slightly big since my waist is boarder line and it turns out it is too big, so I have to use the belt to hold the kilt up. With my wool kilt I don't wear it because I am still adjusting it (the belt) to not slide up my back when I sit.

I have the sporran on a leather pants belt about 1" thick set to the last notch, so I still have that transition between top and bottom.