QF haven't used rear stairs in sydney, Melbourne and most other capital city airports for at least 20 years. I reckon a trial to determine exact manpower requirements, customer feedback, logistical issues, security issues and so on is a great idea. IE, not every bay in sydney is going to be able to do it. How do pax get downstairs after having boarding pass scanned.
So I reckon the trial isn't to see if it works per se, it's to see what needs to be done to expand the concept more widely.
If QF launched straight into it and it was a bit of a bun fight (as I'm sure it was for JQ when they first started but with only a few aircraft the impacts weren't quite so significant) then the PPRUNE crowd would be shellacking them saying 'why didn't they have a trial first'.
