I don't know I was wondering the same thing just bought a SF28 on eBay for $138.50, just wondering if people still use them and if they have any issues that can be fixed or any tweaks to help the run better. Also what kind of power supply is the best and what type of power connectors plugs fit the FS28 just won auction today and need to get a power supply.
Please keep in mind this guide is dated at this point (around 2 years old). To be able to run it you will need to search about authorization fix. When I owned one it did not have to do this.
Before purchasing one of these make sure to get current info. I honestly was suprised to see this bumped up, I did not think many would still be buying this miner