Either we have a bunch of CSS class definitions and download all those once, or we inline them and download each big URL a bunch of times. Without gzip, the first would probably be a win. But we use gzip, so I'm not sure it matters from the client's point of view.

The reflow thing should matter more, but I'm missing something: when would we be adding or removing classes with JS? Wouldn't we render the markup server-side?