Duplicator Pro might be a bit more popular than BackupGuard. We know about 1 link to it since March 2021 and only 1 link to BackupGuard. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
We used to use All in One migration and is a great plugin but I needed an automated solution. We them found backup-guard and been using ever since. Source: about 3 years ago
2, The logical way would be to develop the site on a staging/ dev server then move it to their live site when ready. A few things, again, need to be considered, but, for a straightforward swap, you can use a plugin like Duplicator Pro to 'duplicate' your updated version and overwrite the live site when ready. Source: over 2 years ago
UpdraftPlus - UpdraftPlus is a WordPress backup plugin.
All-in-One WP Migration - Migrating WordPress sites is a challenging and growing process.
WPvivid Backup - Wordpress Developer
XCloner - XCloner is a website backup and restore plugin for WordPress.
Inbound Now - Build Landing pages, manage inbound leads, and create calls to actions to improve marketing with our Inbound Marketing Plugins for WordPress
Snapshot Pro - Backup & Sync