Despite having less than satisfactory support from other paid products, I rolled the dice and went straight for the commercial version of JEvents.
I have never been happier with the quality of the support from a Joomla Extension.
I sent lists of needs and problems and I received succinct, clear solutions and fair comments as to why the product is configured the way that it is.
Ultimately, I have an phenomenally useful calendar and a few hundred very happy users.
It doesn't get much better than this.