Off course the Horizon is pretty much the newest on the market at this moment. It does has a larger throat, which makes the quilting on King sized Quilts so much easier.
I don't own the Horizon, but the Elna 740. Which is made by Janome too and almost exact the same.
I like the different features and are happy with it. Tinker around and get used to it. I'm pretty sure you will love it just as much.
One of the other features I love about it is the lighting. Can it get any better than that?
Keep your sewing machine purring!