I thought I'd jump in here before Actipro gets to your post to let you know that SE WPF does not have feature parity with SE 4 yet. I don't think the build with adornment support has been released yet (should be soon), but that build will at least give you the ability to support current line highlighting and column guides. Custom adornments is going to be a great feature. I do not believe current line highlighting or column guides will be baked in yet, but the groundwork is there.
I've been following the SE WPF development since the very beginning, and it's truly a great product. All the changes that have been made to the core framework (its completely rewritten) are going to make the WPF version so much better than SE 4. The downside, unfortunately, is that coding all these new features from scratch takes time, so you do not have a drop-in replacement for all the old SE 4 features yet. Depending on what you're trying to do, though, you might still be able to implement the WPF version.
There is no conversion guide that I know of, and I imagine that is something that Actipro will work on when SE WPF comes out of beta. Until then, the code base is potentially in flux and the conversion guide could become inaccurate.
I would suggest you come up with a bullet list of features you have to have to replace your SE 4 implementation with SE WPF. Then it should be fairly easy to determine which of those features are implemented, which would require some custom work on your own, and which might be unavailable at this time.