Everything on the older ones was a extra you had to pay for, e.g. mine has wind up rear windows, because you had to pay Ford for the priviledge. Majority is now standard on 2010 spec ST's, lol.
Oil filter housing diaphragm can blow, alternator can go. Liners in the engine can blow if you mod it too high, although less facelift cars seem to have this problem now, but the liners have known to blow on non-modded cars so that's not exclusive to modded cars. Mines a 07 pre-facelift, and close to around 300hp at a guess, and still going ok, the only thing I have wrong is am getting some slight clutch slip in high gear, but that's going to be solved with an RS clutch.
Other than that great cars, cheap to mod, Ford; so easy to repair if it breaks. I love driving mine, although I'm using the bike mroe to save money on petrol so I can buy some more mods, lol.