ShipWorks is a great piece of software. The support is outstanding, very knowledgable and always available by phone to fix any problem. They even customized some features for us and taylored our email and label templates to fit our needs. I could not be happier.
We use a server based installation of ShipWorks that is accessable throughout our IT network so eveyone works off the same database. The system is rock-solid. It is way more stable than out longtime in market "accounting software".
This is one of the best SaaS experience I have had since in the e-commerce business. (7+ years). I only wish it was cloud based so we can work remote when needed.