I would have to say that having a 10 gallon salt water is a little too risky. It would be too easy to screw up on parameters and as we all know....the larger a tank is, the easier it is to keep stable. I have a friend who had a 10 gallon brackish and ran into probs left and right, but on the other hand my other friend has a full blown 20 gallon salt water reef setup and it is completely stable......so I guess it all depends on how much care and attention you are willing to put into it!
However, I wouldn't suggest a 10 gallon salt.