Good summary Matt. I'd also like to suggest
Rails for Java Developers. It's a good book that shows comparisons of Ruby to Java, and Rails Components to common Java frameworks like
Struts and Hibernate. There's no advantage in writing Java with Ruby syntax... and this book helps you avoid that pitfall.
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One interesting performance statistic to look at while developing a Rails app is what your "not" doing. (not configuring, not creating lots of plumbing, not spending a lot of time designing complex object hierarchies, etc). You can then focus that reclaimed time and energy on productive tasks like: creating solid integration tests, fine-tuning your features so that they make sense to your users, refactoring code out of the view into partials/models/helpers/app-helpers/plugins, etc.
Thanks!