I replaced dtregister because it was unstable. The support was slow and frankly kind of annoying.I paid $75 for that component. My customer (saddleupva.com) immediately complained of students not being able to buy classes and zero-dollars where they had been set to $295.
I had already reported several bugs to dtregister. Switching between individual and group registration had created a set of $0 priced records (ack!). The discount code is part of registration rather than billing. Support was slow to non-existant, at one point I waited weeks and only got a response when i threatened to ask my credit card company for a refund.
On the other hand, Event Booking was only $25. It worked the first time with no issues except one. That issue was the failure of joomla to default to the "default.php" view on credit card failure. I found the author on Yahoo chat. He found and fixed the problem within an hour.
The code itself has been solid and done what it says it will do.
I would like to see event_date included in all communications to admin and customers. I mostly made the changes to the code myself. So I got a chance to see the code. Unlike the competitor's code mentioned above, the Event Booking code is solid. It follows standard operating code rules. (For instance, the dtregister issue is obviously a problem with data integrity, it's just sloppy). Event Booking code that I read follows solid academic coding conventions.
I highly recommend Event Booking. It's a good value with well written code and exceptionally good support.
One thing though. The document URL is a predictable pattern. I think this means I can go to everybody's Docman seller site and leech free books.
I'll be happy to hear I'm wrong and turn this Good to an Excellent.