I'll go SLIGHTLY against the flow here, and suggest that actually the type of footbed IS important. But it takes a very good bootfitter to determine what type is best suited for your individual foot, and then to build it correctly for you.
For people, like myself, who have very flexible feet and who pronate, a well-built, very solid footbed molded to an unweighted foot is probably the most effective because it can best stabilize the foot and ankle. Superfeet Kork fit the description, and work well for me. But I've had a couple pairs built that did NOT work, too, because the fitter did not do it right. The SuperFeet currently in my boots are more than 15 years old, and they have probably a couple THOUSAND days of skiing on them!
For someone with a very rigid foot--the classic "supinator"--a more flexible footbed, perhaps molded weighted or semi-weighted, might be better.
So I DO agree that the most important part of the equation is a highly skilled and knowledgeable boot fitter. But part of the skill of the bootfitter is to know what materials and tools are best suited to each individual foot.