My experience mostly following/detailing Sean's 20Jan algorithm:
- Made Opalstack WP app on throwaway/testing subdomain (say: migrate.myaccount.opalstacked.com). I UNTICKED the default <site URL managed>, not sure if this matters or not.
- With FileZilla deleted all files in the app and uploaded AkeebaBackup WP archive (.jpa) and unpacker (kickstart.php) with most settings obvious (db, username, ... ) and/or already correctly ticked (e.g., SetHandler will be deleted from the .htaccess, see https://community.opalstack.com/d/44-wordpress-white-screen-limitinternalrecursion-error ). DIFFERENCE: I unticked all database replacements of (old-live-url) to (new-test-url) because eventually will delete test-domain anyhow. If the old website has "wp-" as table prefix, don't fix that during migration as some parameter values will get screwed up (e.g. an uncommon plugin with "wp-" in its name messing up autoreplace in pref_options & pref_usermeta).
- No step3 as AkeebaBackup already did.
- 5. 6. 7. 8. Unchanged.
I'm using AkeebaBackupWP because I'm used to AkeebaBackup for Joomla, where they have a reputation for very good quality code and development. The WP version doesn't appear in the WP plugins list for reasons they explain, so downloaded directly from their website.
I used to have Duplicator but hated their setup often (an installerscript+archive pair, just like Akeeba, but the script is unique to the archive for no good reason; and without datetime stamp and siteURL automatically appended to the script name, matching it to its archive was a nuisance). Also (non-WebFaction issue!) larger WP site the "Duplicator Package" creation error'ed out for using too much resources.
On a sidenote, when you're trying multiple cloning/backup plugins, each inadvertently backs up the other's backups so it gets inordinately large if you forget (or cannot) exclude the others' backup location when making an archive/backup/package/whatsamacallit.
I tried WP Staging but that seemed to insist on a staging sub-directory not allowing migration/staging on independent domain as needed here. [Maybe my fault, interpreting "staging" too broadly.]
In any case I'd suggest a look at AkeebaBackup-for-WP to minimize the (Sean's words) "migrate a site without some sort of export/download/upload/import" dance. I find their options both before (configuration) and after (during restore) vastly more clear and useful.