I installed it and had no issues with it. It has a few quirks but is serviceable.
The thing is that I don't actually use it to manage my PRS-300 and don't even have it installed on my Mac, which is my primary computer. I use Calibre to manage my ereader. The Sony software is installed on my netbook and is only used for purchasing ebooks. I also have the Kindle for PC software installed on there. I just de-DRM the files and email them to myself and then put them into Calibre on my Mac.
So I chose the first, third, and fifth options since those all apply