Node.js vs Java for Comet application

We look to build a high-performance, scalable Comet server, and thought first about using Java Grizzly with GlassFish.

But after some research, we see that Node.JS is taking rapidly as the preferred choice due to extreme simplicity, and claimed performance:

http://news.ycombinator.com/item?id=1088699

http://amix.dk/blog/post/19484

I will be happy to hear some real-life experience of using both, and what ultimately can be the best choice down the road.

Thanks!