An early support mail was replied with a totally adequate answer in a few hours on a weekend day, which clearly exceeded my expectation.
In a nutshell, I warmly recommend this extension.
I still have an outstanding support issue, but it may be caused by IE9 being a non-standard browser more than this extension. Anyway, it's currently under investigation, and it won't decrease my rating.
All in all, the rookie in me loves it. Great job, Cedric !