As someone that used to have to wear a cumberbund for work, I hate the wee buggers and would never wear one with a kilt. With a traditional kilt, the waist is higher that pants. The top of the kilt actually comes to about the same level as a cumberbund does with pants. It kind of becomes a moot point if the kilt already comes up quite high. If you don't want to wear a waistcoat, I would suggest just a belt, but not a cumberbund.