Simply put, the ONLY criteria one can logically have as to whether to buy S3 or not is what it has with it...one circuit. Anything more or less is illogical, and unfounded. You cannot safely use any past happenings to decide whether 12 GBP are worth it now or not. "Past Performance is not indicative of Future Results" is the phrase that comes to mind.
To my mind, there is NOTHING wrong with the current package of LFS. Slow development or not, it was always there for use, be it leagues or offline or pickup. The potential was always there, just the slow development took out basically everything as collateral. The fact that people still put in effort to organize events and still have people showing up, although numbers are poor, shows that it's still a solid foundation. The structure is still there, this is just an addition to the already existing house. The entire thing isn't destroyed because of the possibility to add another thing.
It flies in the face of those who still try to run events to have people call the game "dead". It is unquestionably the MINDSET of the community which is dead, NOT the game. Every time someone comes back to LFS to try a new thing in the past few months, I see them say "Wow! I forgot how fun LFS is!" after they spend time in a server with others trying same new thing. It's not the sign of a dead game, it's the sign of a dead, feckless community.