Great piece of software, but I very nearly uninstalled it.
The trial version has a humming noise or sine wave in the background. While I fully understand why it is there, I do think that it would be better if you made people aware of it as one of the limitations of the trial version.
I thought it was an issue with the setup I had and dismissed Playbeat because of this in favour of another plugin. However I gave Playbeat another go, and after routing around in the forum I found that the hum is limited to the trial version only.
If you could add it to the list of trial limitations then I think people would quite accept that it is there and not dismiss Playbeat as I very nearly did!