I have the Memory Craft 6600P and tho it isn't an embroidery machine I can tell you that it's a wonderful quilting friend. I've worked on projects for up to 8 hours straight without a single problem. I wouldn't part with my Janome for anything! So tho I can't offer advice about embroidery, I know you've made a great choice in brand names.
Have you checked out Janome's website? You can do a side-by-side comparison of models and features there. Most of the larger machines for quilting and embroidery have at least a 9" throat, but you can find the measurements there. The larger, the better!