I had was disappointed because RSTickets! almost fit the bill, but lacked some critical functionality we required. When RSTickets! Pro was released, I was ecstatic. Not only did it meet our requirements with extra functionality, but exceeded them. I had some initial difficulties with my installation, but RSJoomla identified the problem and got me up and running quickly. (The problem wasn't even with RSTickets! Pro, it was with a plugin which was creating a conflict, and they provided a fix for the plugin!)
If I could give these guys 10 stars out of 5, I would! Thanks!