I have an 850, and I have mixed feelings about it.
My advice on the machine is to make sure your dealer is someone you feel comfortable turning to if you have a problem. Mine basically shoved the box in my arms and showed me the door. Sapphire owners with responsible dealers seem have a better experience!
There's also a Yahoo group for Viking Sapphire owners that is a great resource, even if you only read the old posts. They are enthusiastic about loving their machines.
Good luck with your decision.