I've had ruby aliased to rbx on my own personal laptop and run all of my development on rbx, I only have to bust out MRI every once in a while, like once a month. I write lots of code with event machine, redis, amqp and many other complex parts of ruby ecosystem and for the most part they all just work on rbx.
Huge congrats to rubinius team again, I predict this will be the default ruby for most people inside of a year if not 6 months.
Rubinius is ruby done right IMHO.