We are an NGO with international educational projects. The tool is used to engage with our donors, partners and the press. Our small team updates the information in our contact lists and I use it to send normal campaigns and drip campaigns. We capture information on our website but also synchronise with external databases we use for offline and online donations.
7Sheep works very well for a small NGO like us. If you need to integrate a lot of systems this works via the API but you need a developer for that, or ask their support. In general you can use the tool without internal IT staff as it's easy to implement and their support is helpful. You can only use it if you are allowed to store your data in the cloud.