That's been my experience as well. I prefer Rails over most Java frameworks as well due to all the sugar that comes with a fully integrated webdev stack.
As far as scaling, no problems so far (but this is a relatively small app). To me, as long as a certain response time is met, it's not nearly as important as being agile and organized.
All the frameworks have trade offs. But to me, Rails seems like a good place to be not only because of its technical merits, but also because its strong and innovative community...which is constantly improving the framework (as well as Ruby itself).
If you're looking for performance, ruby is not the place to look. Ruby/Rails is for faster development with good organization, with much less chance of having sphagetti code (like PHP) which results in easier maintenance and evolution.