What this guy said!
I wouldn't let all the horror stories put you off, there are ways around the security issues. The power writer software isn't the same for all the versions of the f-con though. there should be a coloured round sticker onn the front of the unit to show which version it is, or you can be doubly sure by checking your serial number against the ones listed on the HKS Europe website.
I also have the Hks wideband/knock sensor which I personally think makes for a great set up.
This obviously is dependent of the price you will be paying for the fcon your interested in buying, I went down this route because I feel the f-con has a lot to offer (when you can use it) and can be purchased relatively cheap compared to other ecu's out there.