As I said: I'm all for adopting new technologies (newer projects than this web application were done in Python 3 and lately node.js).

I'm also reluctant though to introduce more dependencies for the sake of porting perfectly working code to another language I might like more.

It's not just that maintenance will be harder it's also that in some cases our customers (very traditional enterprise. IE6-on-NT4-traditional) provide the server for this to run on and I can't present them with a huge list of services to install and monitor.

Well. Maybe I could, but I my conscience can't deal with persenting them with that list just so that I potentially have more fun while programming.

One of the things I'm currently looking into though is Websockets for a specific component of the app and in that case, I SO clearly see a huge advantage in Node.js that I will certainly go node if we decide that the shortcomings in the way we are currently solving that problem warrant the change in the architecture.

Which brings me to the same conclusion as my initial post:

Rewrite for additional functionality or fixed issues: Yeah. Rewrite for the sake of having it rewritten: I'd rather not.