The MRI C extension API compatibility is very much an official feature. Except for a few gems we can't make work (because they tie directly into 1.8's execution model) most work fine. If you have one that doesn't work, please just open an issue and we'll figure it out!
Been a long time coming, with a lot of blood sweat and tears on your part, but it looks like Rubinius2 is the project I was lusting after those years ago, back when it looked like Sydney was the fix for what ailed Ruby. ;-)
