Nice writeup Sarah.

This is essentially all the flexibility of WordPress.org with the support and reliability you’d expect from WordPress.com

I don't consider that to be true. WordPress.com has a huge advantage in that they control all of the code. That's a fundamental difference and an important one. WordPress.com lacks functionality and control, but it has better stability because of it. I don't think any system which gives the user access to the file system or which replicates the file system for each user will ever be that stable. There's just too many points of failure.

That's not a net negative for the Ghost hosted service, I just don't think the two are comparable in that sort of way.