Everyone seems to be saying the same thing, but I have one thing to add. Yes, a stand-alone environment is, I guess, sufficient for a development environment. However, for my set-up, I mimicked a stand-alone by choosing a farm installation, but installed everything on one machine. Why? By going down the default, stand-alone route, SQL Express is installed, and with that you have the limitations that come with it. Further, I recall from some of my research on the topic that there is no way to branch out to a farm environment from a the default, stand-alone installation. On the other hand, one very likely may never do that kind of migration in a dev environment, but I for one would never want to limit myself.