Which features should you look for in an upper end sewing machine?

So you’ve finally decided to take the plunge and buy yourself a fancy schmancy, whizz bang, make-your-sewing-friends-jealous sewing machine. There are many models to choose from and they’re all loaded with features, features, features. Which features are a must? Which just sound nice on the packaging? Sew4Home shares some advice in their article, Top Ten Advanced Machine Features.