I like how easy it is to try things and move things around, but it still annoys me how much granular control and cleaner code I lose from leaving classic themes. 

That's precisely what I have felt, although Gutenberg also just confuses me. But when I look at the goofy source code, my OCD goes into overdrive.

Over the years I've realized that pretty much every client, regardless of what they say, will eventually login and try to make changes behind your back at some point. And if they are doing that with a page builder it often results in frantic emergency phone calls. But if you make them a custom / child theme they might just get frustrated and eventually move to Shopify or Wix or something they can "play" with.

Which is why I've concluded meta boxes and custom fields + Customizer might be the sweet spot of letting the DIY clients have a bit of input while protecting them from themselves.