Have had many high performance cars, always bought used (less than 50K miles) and always changed the fluids soon after buying them, cheap insurance and nothing like fresh fluids for your machine.
Though I personally never had any transmission issues but several years of various forums (Porsche/Audi/Mercedes), it's never a good idea for full flush, always drain and fill.
Just bought a '12 X5M with 40k miles and will be going through all the fluids as soon as I decide if it's a keeper or not
