Litmus is great, you should get Litmus!

We use Litmus to build, maintain and manage our email design system, iterate on email templates and build campaigns from start to finish. We also use Litmus Proof for internal validation and approvals, before transferring campaigns to our ESP. Lastly, we perform Q&A tests on campaigns sent from our ESP to Litmus, to ensure emails are rendering correctly.

We don't have access to Litmus Analytics, so can't say.

Litmus Proof has really helped streamline getting content signed off, gone is the complicated process of having to get full-screen screenshots sorted and lots of zooming and folk can comment directly on areas that they care about.