We use 7Sheep at a startup which has professional photographers as clients. Marketing Automation is used to capture leads on our website and put them in a drip campaign. Another drip campaign is used when people sign up for our tool. As we are a small team everyone has access to 7Sheep.
I think 7Sheep is a great tool for a startup. We can focus on our software and do not need to implement everything on our own. If you can integrate your software via the API it is even more amazing. 7Sheep is well suited for small teams. Larger teams should evaluate if the user management is detailed enough.