Hi there Behelden. Thanks for the note here, and for posting this review - we're sorry to hear we've let you down with the plugin. Please know every time we receive a review like this, we view it as a failing on ourselves and I'm sorry we didn't deliver what you'd expected.
I will say, it sounds like you have been faced with some unique problems here. I'm not sure what you mean by "you cannot select which event details show in the listing without hacking code," but you can decide what shows in events on an event-by-event basis. Totally understand your point about changing display characteristics and backing up, though. The display characteristics issue - and the fact that it requires template overrides to implement - was a decision we made to give themers greater flexibility to modify as they see fit (but to allow an out-of-the-box solution for those who want one as well). For backups, you raise an interesting point...we generally hadn't considered building a backup-centric solution into the plugin itself, since most of us use solutions like Backup Buddy to handle site-wide backups, but you raise a good point that gives us something new to discuss. Thanks, on that end.
Lastly, to shed some light regarding support: we do help users reporting legitimate bugs, that we can recreate, who report those here on the dot-org forum. Our policy up until now has been to hit dot-org once every 1-2 weeks to check for bug reports and get those logged/addressed as they come through. We're unfortunately not in a position where we can provide free/non-paying users with the level of support we offer paying users. I'm not sure what you were getting at with "There seems to be no upgrade path beyond pay and pay again", but if you saw an upgrade message you obviously aren't going to be forced to pay again to get rid of it. Was probably just a version mismatch issue which is relatively easy to rectify.
All that to say - sorry we let you down, and thanks for taking the time to give this feedback so we know where we need to improve. Best of luck with finding another calendar solution that meets your needs.