Concerns about managing the whole server stack vs. relying on managed hosting

Hi @evanfuture (and all other folks interested on that topic), I react to your comment on this 8 months old post to get a feedback on your migration from WPEngine to Trellis/DigitalOcean. I hesitate to do the same for weeks.
I decided to create a new topic as the one I mentioned has a pretty different title.

I have two concerns about taking care of the entire server stack:

  1. During the last 8 months, did you face infrastructure issue? I mean, did you face issues that wouldn’t occur with WPEngine or Siteground (install security updates, firewall issue/tuning or whatever). How many time did you spend on this?
  2. How to sell this kind of hosting to client: How to argue if they require access to the host as there is no cpanel (it’s possible to install it but I guess it’s not a good idea), how to reassure them if they ask "what if I’d like to migrate my site to a competitor / another hosting company? What’s going to happen at the end of the warranty or maintenance period?

I’m planning to manage/create at least 15~20 sites per year (or more). Do you think Trellis/DO is the couple for that?

I’m very curious to read your comments !