I have a number of waistcoats that I wear with my tweed kilt jackets, some of them match, some of them don't. Of the non matching ones, they tend to be doeskin or harris tweed, in greens or browns. As has been said, I think that the need of matching of your jacket and waistcoat increases with the level of formality of your event. Apart from scottish attire it is very rare to see any gentlemen wearing a waistcoat with a jacket these days, at least in Australia that is.