I also have aJanome 660 and wanted to do more embroidery -- only I went the other way and bought the Brother Quattro 6000. It is fantastic -- does everything but wash windows! Originally I thought to trade in my Janome, but glad I kept it and use the two side-by-side.
As far as getting a new embroidery machine, get one that you can get support and instructions. Nothing is more frustrating than fumbling around computer screens not knowing where to go or what to push. Get one with the biggest hoop you can afford or you will find yourself outgrowing it too soon.