I had a Viking 400 for about 15 years. It finally gave out and would have been a few hundred dollars to fix. I decided to get a new one and bought a Viking Sapphire 830. I've been very happy with the Vikings. I had a Kenmore before the first Viking and it was ok, but prefer the Vikings. The Sapphire is so different, it takes some getting used to, but I am pleased with it. I did look at the Emerald, but it was only $100 more to get the Sapphire, and with the bigger throat, I decided to go for it.
Just be sure to test drive the features you will most likely use, not just the pretty stitches. You'll get a better idea of whether or not you like it that way.
Good luck!