I recently launched a site that uses the pro version of this plugin. (kenhatfield.com) We loaded 9 albums of music.
This plugin works in all browsers that we tested including Firefox, due to the inclusion of mp3 and .ogg file,s and also plays well on the iPhone and iPad.
We incorporated a Paypal store and set up links for CD purchase, digital album purchase and digital download of songs. (Using FetchApp) Everything works perfectly, the pro version is an excellent product that I recommend without reservation.
For future updates, I suggest an option that would allow an excel upload to manage the song list which would greatly reduce the time to load songs.