One thing to keep in mind is to have the same platform to develop on and to deploy on (ie. server and your local workstation). Iojs and node.js have some (few) modules that do not work well accross the platforms, so you'd have to match those. Example, with some versions of mongoose I've had issues - stuff precompiled for Node would not work on Io or the other way around. Also, gulp has had some issues.
Another thing is stability. I would say iojs is stable, but they themselves are saying it's not production ready. I know that's just CYA talk, but I've listened to that advice and I use Node on production.