Thanks for your replies!
I do understand that the "net boot"part of architect is one of the key benefits of it.
At the moment I want to install 3 different tries in 1 hour, so I created a small script that I run before starting architect (“setup”). I mounts an NFS share to /var/cache/pacman and then uses that on consecutive installs. I placed this script on my web server and call it using curl http://webserver|sudo bash. It might be a bit blunt, but it works: 
Did also look into adapting Calamares to make it use refind but that is not trivial (meaning: needs me to read up on a lot of documents, which someday I might )
I jumped ship (from Ubuntu to Manjaro ) in May, so just about half a year now. And still find new things to be happy about in Manjaro (Architect being one)