I have no experience with this platform but some thoughts after a quick look at the demo site/admin: Despite the dated look of the demo site, the extension repository seems fairly active. The GitHub repo is filled with lots of recent commits and issues. They support modern versions of PHP. Lots of documentation. All good signs that I wish I saw more often... The content editor on the demo is "old-school" compared to the explosion of block editors and builders in the WordPress world. That may not be an issue for your client. The demo admin seems really clean and fast. If you find extensions that do what you need, or find the learning curve for a custom plugin to be reasonable, then it seems worth a shot. I hope you'll report back to us if you go that route.