I've had my 2.5 for 5 years, it's a 53 plate with 88k miles. I've replaced the pads and discs myself, change the oil and filter every year and the air filter when required. I've done about 35k miles while I've owned it and had no issues whatsoever, except the roof motor which needs replacing!
For me the 2.5 is more than enough, done about 6 long weekends over to France and beyond and the car makes for a great journey. Trips have included numerous to the Nurburgring, where again for me, the car is well up to the job.
In hindsight, I don't regret no getting a 3.0, but do wish I'd got a higher spec version, with cruise and cup holders.
Good luck with your purchase.