I have a Janome 350 and love it! I would definitely recommend it over the 200 because of the larger hoop and the thread cutter (a real godsend for embroidery, where you are changing thread frequently).
I don't know anything about the Viking or Elna, but I would rather have a dedicated embroidery machine than a combination sewing/embroidery machine. I love combining embroidery with quilting, and with the separate embroidery machine, I can be making the embroidery design on it, while I am sewing on my Janome 6600.
I bought the software with the 350, but have never used it! It's too complicated--or I haven't torn myself away from the machines long enough to take the time to learn. I get my embroidery designs online, which eliminates the need to design them myself. There are so many designs online that are free, or very inexpensive, so it isn't worth the time and effort for me to design my own.
You can get a Gigahoop (large hoop) for the 350, but I've never felt the need for it. The large hoop that comes with the 350 is big enough for me.
If you have any questions, feel free to ask. And Good Luck--you will love the world of embroidery!