This is something I’m really looking forward to as well. I have every customer sign a service form before performing a repair. With my current accounting software, I have the option to attach the scanned file to my invoice.
I like the ease of use and workflow of your software better than my current accounting software, however this and the add customer from invoice creation page are the two things that are keeping me with my current software.
The moment these two features are added, you will have another customer for your Cloud accounting service.