A never mentioned but crucial issue with Cloudflare is that you are required to use their nameservers; you cannot change to use third party NS without transferring out.
> All domains using Cloudflare Registrar must use Cloudflare DNS on a full setup. This also means that you cannot change to another DNS provider while using Cloudflare Registrar.
> We built our registrar specifically for customers who want to use other Cloudflare products. This means domains registered with Cloudflare can only use our nameservers. If your domain requires non-Cloudflare nameservers then we’re not the right registrar for you.