Hi, Ryan,

Thank you for your inquiry.

• Way to add multiple Attendees into attendance sheets(Multi select) rather than 1 at a time. - Yes, it is possible to have Appointments with a Capacity >1 in Amelia.
• Generate report on customers and financial data. - It depends on which kind of reports you are looking for. For example, Amelia doesn't store Customer's payment information, therefore it's possible to see only the status of the payment and the paid amount in Amelia. Also, you can filter payments by the Employee name, the Service, the Customer, and the payment Status. But there are no detailed reports with statistics, I'm afraid. 
• Take custom data fields and add them to reports. - I'm afraid, only built-in fields can be included in reports at the moment.
• Edit users details on the fly - Yes, it is possible to edit user's details on the back-end.

I'd like to mention that we have a 15 days money-back guarantee, which means you can purchase Amelia, test it, and if it turns out Amelia doesn't fit your business, you can request a money refund within 15 days after the purchase.

Please let us know if you have any other questions.

Best Regards.