Have purchased and have tried several SMS solutions over the past few years including a number of SMS products that have been on AppSumo. This is a really feature rich product and works right out of the box. Tutorials aren't too bad but they're basic. For documentation it would be extremely helpful to have some architecture type of documentation and some information that describe how the product can be used for different customer/agency situations. A point of note that an "agency" would in most cases actually be a customer and for each 'customer/agency' you can have up to 50 team members. You can have multiple numbers per agency and there are lots of functionality for automation and list management. A caution that email integration is currently limited to Mailchimp, GetResponse, ActiveCampaign, Aweber and Sendinblue. There isn't any other SMTP support.
Support / Help Desk very responsive.
No white labelling of the product is possible according to support staff and it is not something that will be available in the future.
Super product and highly recommended!
All that is needed now is a phone app and some use case documentation. :)