Hey Binastro (post 20),
When following fast moving birds you rarely can acquire perfect focus, so you must rely on a general impression and this is where good ID skills come in.
This is why I like lower powered binoculars b/c you get a slightly less shaky image. You can't look for warblers with a tripod obviously but you could do this for ducks and geese in fields; static type of birding. When IS bins are improved enough to the point where they work great with glasses, are lighter and better ergonomically and have super long battery life I would consider buying one.