Thanks Graeme, I totally agree with your points. I too wouldn't choose anything other than pen and paper on-site - which is why I've designed on-site printable forms that take a fresh approach to the process which (from my personal experience so far) speed up that side of the process. I expect the feedback regarding price point to come in similar to what you've said.
Emailing certificates with digital signatures to clients surely is a time saver - granted, carbon pads can be handed over immediately, but if dealing with letting agencies for example, doing PIRs on a regular basis could be simplified with email. Not to mention producing duplicates & converting all data into an installation certificate.
The software I am designing is trying to take a new approach - simplifying the forms layout, speeding up the in-office admin time for typing up certs & concentrating on the user's experience...
I hope you take another look further into the development process and can give me some feedback then. =)