In some instances, a company will extend their one year warranty on skis to two years if you use a pair of their bindings on a pair of their skis.
As to boots, the brands each seem to have their own unique fit and shape. For example, I am told that the Nordica Doberman line is very narrow, while the Dolomite line is high volume. All boots should fit the same in all bindings, so that's not the problem. The goal is to fit the boot to your unique foot. Thus, it would seem that the brand of boot you buy should depend completely on your foot and your physical and ability characteristics as a skier and not at all on the brand of skis and bindings you use.