We're the developers of the app and we're happy to take questions / answer queries.

- On the "scan by any scanner" issue; We're looking into this, but at the moment only PayPals servers are used, so using an intermediary will introduce complexity and potentially increase QR code density to beyond what can be shown well on a QVGA Screen (yup, we test on a Tattoo). But we are looking into it.

- On the "Crafted URL" issue; We use the Adaptive API which allows us to include multiple recipients and other features which can't be done with the crafted URL. We're also talking to PayPal about using their upcoming Android PayPal library which will give a better user experience that can't be duplicated with one URL.

Any other suggestions / comments / etc. welcome (and thanks for the mention Android Guys).