I talked to Untangle sales and they are very friendly and knowledgeable. I re-reviewed the X series (u50x) and the specs seem adequate for less than 10 users.
Feel free to comment if you have used this or think this is OR is not adequate?
Untangle U50X
Intel Celeron 3215U 1.7 GHz dual core processor
4GB RAM
128GB mSATA SSD