+ eleventy for the S3. I’ve been using them since the S-1 came out (One of those lasted three bikes, including two DH bikes. I eventually sold it with a frame and fork, and it’s probably still going strong somewhere. I’ve just swapped out a King (gasp!) for an S3 because the King kept loosening – it’s on a 5″ travel fork, and I guess the new King compression washers will make the difference if/when they come out, but an S3 just sort of goes on and stays on. Occasionally I put a new cartridge bearing in, but otherwise it just works. I love the King headset, but not when it needs constant tweaking – very frustrating!
Cynic-Al – is it possible you’ve ovalised the headset cups or head tube?
Oh, and I’ve got a second hand Hope on another bike that seems to be pretty much maintenance free too.