Ask HN: SendGrid Transactional Templates, or no?

Has anyone here used SendGrid's Transactional Templates feature before, and what are you thoughts on it? And in comparison to building your email templates in your application directly?

It seems the Pro is that the template work can be offloaded to designers/marketers and developers only need to reference the right template in their code, they don't have to write the template code themselves. The Con is that the templates live in SendGrid, making it difficult to move to another email provider in the future if there was a reason to, as you'd have to redo the templates in the next provider, or reimplement it in your application.

Thoughts?

SendGrid Transactional Templates: https://sendgrid.com/docs/User_Guide/Transactional_Templates/index.html