I’ve managed hundreds of Magento, WordPress, and Shopify sites. In that mix, there’s been maybe half a dozen Drupal sites.

My experience is very limited. All I can say of my experience is I am glad that ratio was as low as it was. The last time I touched a Drupal site, deupal 8 was new. I did not like it as a content management platform.

Take this with a grain of salt. My inexperience with the platform could well be the source of my own frustration. theyre also on Drupal 10 now.

Drupal is a bit of a beast. It takes a lot of experience to keep one of these alive over time when major version updates will break plug-ins and custom code. I’d recommend either keeping it very vanilla or having a “guy” who’s either a drupal dev or has some experience with migrations. It’s fine to self-host, but handling those upgrades isn’t always easy.

I’d say try to push Wordpress as much as possible, and only go drupal if you absolutely need the features, but try to avoid customizations that add schemas or complex data structures.

It’s fine.

Like any CMS, it has a seemingly constant low level of patching to be applied. The more third party modules and themes you have, the worse that gets.

Remove unused modules that aren’t core. Same with themes. That’ll make things easier.

Otherwise it’s overheads are just Apache/nginx, MySQL/MariaDb, and maintenance of the TLS certificate, plus OS patching. All fairly well understood stuff that you should have no issues with.

Depending on your needs, a static file CMS may be a good fit. We’ve been using Grav CMS with great success to retire a bunch of Drupal and Wordpress sites. For simple sites, it was a no brainer.

If you want to use a CMS that runs on PHP, take a look at Processwire. It’s flexible, intuitive and (if such things matter) fun to code for.

Downside being that it’s not well known although it’s been around a long time.