I guess that's the darkest fear of many people inside the business too, that any float might dilute the unique character of the company. There'd no doubt have to be a few concessions to the public bit of being a plc, but ultimately, it's the unconventional, fun, irreverent employee-centric culture of the business that has been central to the fantastic growth and profitability.
You don't have to turn into a grey corporate behemoth when you go public - look at Google, $390bn market cap and still a much-admired employer and an undeniably funky and innovative workplace. http://www.telegraph.co.uk/technology/picture-galleries/9461561/Inside-Googles-quirky-new-London-headquarters.html?frame=2303595