Insist on exclusivity agreements on custom solutions built by systems integrators; you don't want the solution to be repackaged and sold to competitors.
DMA is a SaaS success story, having taken an aggressive and smart approach to moving its systems out into the cloud, beginning in 2001. The company credits the strategy with allowing it to better compete with larger firms in its industry, food distribution. DMA CEO Bob Sala has employed these principles in his company’s 10 years of experience with software-as-a-service. Look for each in your SaaS engagements.