of course you guys know my vegemite comments were slightly in jest. Well sort of, vegemite is quite a serious culinary subject down-under. IMO, Marmite should never be linked with vegemite ... I love V, but Marmite is one of the worst tasting spreads I have ever tasted. Ultimately it is about personal preference, I have only met a couple of people who like both, it's always one or the other, or neither.
I can highly recommend Vegemite and cheese. Vegemite and peanut butter is something I have never tried. I like both individually but the though of combining them seems just plain weird.