[stern]

>The advantage of the download (desktop version) is that users can run in a borderless window with six color schemes and the ability to close the side palette.

Is this really an advantage? I'd want to confirm with potential users that they are concerned with color schemes (as I know I'd never pay for color) and having it in a borderless window as opposed to an additional tab in an already open FireFox.

You really need to define the additional advantage of the pay vs non-pay version. What is the screaming need in your users lives that paying $15 is going to solve?