I juggle two day jobs, both for responsive, background-processing-heavy websites. One's in Node and one's in Scala (Java on steroids). To me, the Node way Makes More Sense.
Yes, Java can process in multiple threads at once; but then you need to worry about atomicity. Yes, Java it can delegate different jobs to different threads; but then you need to read up on ExecutorServices. Yes, Java is faster; but if you want async file reads, things get complicated pretty quickly. (If you're going to block your thread, you'd better adjust your thread pool....) Yes, Java is type-safe and compiled; but that hinders as often as it helps.
These are two different cultures. Java culture seems to whirl around huge infrastructures -- J2EE, JDBC, Swing, Ant, etc -- that have gargantuan learning curves and ten-year-old flaws. (One that bit me: Java 7's UTF-8 decoder accepts invalid UTF-8 to maintain compatibility with Java 5 -- that is, a ten-year-old version of the standard.)
In contrast, Node culture is about self-organizing chaos. You can deliver results really quickly, but you might need to rewrite your code in a few months to keep up with library changes. And your favourite dependency might not be there tomorrow.