I have both the KMD150 and the 496 and can't imagine giving up either one, they are really different animals though. The 150 makes navigation in the class B a breeze and from strictly a navigation point of view I prefer the 150. The 496 is the brains of the operation, it gives you so much more other info that I use it constantly to keep up with weather, freqs, runways, music and all the other super neat stuff it has. As far as I'm concerned both are an absolute necessity and can't imagine being without either one!