Any oversteer can be dialled out with a decent geo - personally I've never experienced it in mine. Now with nearly 20,000 miles on the clock, and some 60 odd track days, there is generally very little that goes wrong. I've had a sensor fail which brought the rev limiter in too early as the car thought it was running hot, and it needed a new accelerator linkage which was done under warranty, as was the radiator which showed signs of seepage before the car was a year old. I've heard of one car with a slight oil leak from the supercharger. Mine had a slight leak from the Accusump filter which I believe was a recall issue and sorted on all cars.
The cars don't really have service intervals as they are rarely used as road cars. Instead they have regular track checks. Mine gets looked over after every day, checked properly at the dealer after every three days including twice yearlyclutch/brake fluid changes, sometimes more frequent if I do a lot of days, oil changes after every 3 or 4 days dependent on how hard I drove and the circuit, gearbox oil changed annually. The book says the shocks should be serviced every 2yrs or 10k miles iirc - I had mine completely rebuilt at 3yrs, though they weren't leaking or anything. If you have a search through you'll find other points people say to look out for. I also had a Moroso sump fitted and uprated the engine mounts with polyeurathane (sp?) inserts, plus a Letsla linkage to improve the gear change. Make sure it's had the ECU reflash too.