Is it good to use gevent-socketio to replace native Socket.io/Node.js code? What are your thoughts on this?
This really depends on what you're trying to create and the tools and languages in which you're used to.
I can tell you that Node.js and Socket.IO is a very strong combination, easy to learn and very efficient. However if you're more experienced with Gevent, and time is of priority stick to what you know.
This thread shows a basic comparison between Gevent and Node server: http://groups.google.com/group/gevent/browse_thread/thread/a1d48014d8fd310f?pli=1
Have you considered using Tornado/TornadIO2? They're well-maintained, stable, and work great. I tried using gevent-based implementation first and run into various problems (when used with Django) but had much more success using TornadIO2 and would highly recommend them.