"amount of time spent preparing and delivering an average moodle 'class' "
I guess that I am not really using Moodle to deliver an online classroom, just expanding the walls of my existing, traditional class with some Moodle activities.
Generally after a classroom teaching period, I will spend about 10 min doing some moodle work. This may involve shadowing the class lesson with a Moodle discussion forum, open questions in an online text assignment, suplementary resources to read or perhaps a revision quiz. I may prompt the next class with a choice, forum post etc. During classtime, I may spend about 10 min to initiate a wiki, group chat session or collaborative glossary building task. Some work is online, some is in small groups but the digital artefacts are collected online.
I probably spend 10 min between classes with some cursory reading, grading and giving feedback to students about their contributions. I also do this "face to face" as they watch me review and annotate their work.
Because Moodle has opened a window to a wider world outside the classroom, I can slow the pace down a bit in my regular classes so that we can enjoy the interaction and fresh air.