There are a lot of farm and flock management systems out there. Why would you choose LambTracker over one that is supported by a commercial company?
The main reason is flexibility. Open source software gives you the flexibility to adapt and modify the package to suit your needs.
LambTracker is really best suited for a small to medium size flock that tracks individual sheep at extreme levels of data collection and detail. It would generally only be a purebred or registered flock that might require this level of data collection.