Just like you mentioned, most technology has it's place. It's about finding the right tool for the right job. You are correct that the documentation on the site feels a little strange, but it could have been done better with either technology. Famo.us will stand out for building apps that look like desktop/mobile apps, and not apps that look like webpages. It will also be a wonderful choice for games.
Though I have little familiarity with how meteor rendering works, The ideas around using Famo.us for what you may need should be the same. The most important thing not to do in Famo.us is to battle the Context object. Battling is never good. I threw together a quick example that brought back the default browser scrollbars. You simply use a single surface as your 'body-wrapper' div, and set it's overflow property to scroll. Then inject the rest of the HTML into that surface.
var Engine = require('famous/core/Engine');
var Surface = require('famous/core/Surface');
var context = Engine.createContext();
var context_size = context.getSize();
lorem = "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod\ntempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,\nquis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo\nconsequat. Duis aute irure dolor in reprehenderit in voluptate velit esse\ncillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non\nproident, sunt in culpa qui officia deserunt mollit anim id est laborum.";
content = "<div style='overflow:scroll;width:100%;height:100%'><div style='width:100%;height:200%;background-color:#aaffaa;font-size:72px;line-height:72px'>" + lorem + "</div></div>";
surface = new Surface({
size: context_size,
content: content
});
context.add(surface);
There are few other ways you could incorporate Famo.us elements into webpages. Similar to how Facebook widgets work, you could simply use an iframe.. This goes either way. You could host a Famo.us widget and inject it into an HTML website, or you could inject an html document into a Famo.us app.
Also remember Famo.us is still just a baby. They want to hear your feedback. I assume there will be a lot on using Famo.us for more fluid layouts similar to those that can be achieved with the box-model.
I hope some of this helped!
Good Luck!