I wanted to post one more testimonial that early clunking happened to a lot of us, and almost always evolves away into a non issue. I had a lot of clunking during the first month, and it really worried me at first. I still had a little over the next few months, and occasionally for a year or so. I believe that it is all just a matter of the muscles healing and strengthening. At three years, it is no longer an issue at all.
I also wanted to throw out an idea that may not be popular, but it is worth considering. There have been studies done with cadavers showing that with resurfacing, there can be impingement when taken into extreme flexion, particularly with internal rotation. Some of these studies took the position that this impingement is the norm with resurfacing. This may not be a huge problem, but the argument is that in deep flexion, this impingement levers the ball slightly out of the socket; not enough to come close to dislocation, but enough to unnaturally stretch the muscles and ligaments that hold the joint together. This may lead to a clunk when the ball settles back in place as the person comes out of the stretch, and may arguably lead to more occasional clunking later, since the integrity of the ball being held tightly in the socket may be compromised each time the ball is leveraged slightly from its seated position in the socket. I had a resurfacing friend who, a year or two after surgery, started working with people who believed in extreme flexibility. He started experiencing clunking for the first time during some of the stretches, and sometimes afterwards. In a worst case scenario, some studies expressed theoretical concerns that pushing through this impingement could lead to notching or fracture of the femoral neck, or levering the cup loose. As I understand it, the lower coverage angle in the ASR cups was an attempt to minimize this impingement issue, but we all know that it came with undesired side affects.
So my own non-medical takeaway from all of this as far as clunking is concerned, is that strengthening is good, regaining a "natural" range of motion is good, and pushing for extreme ranges of motion with a resurfacing device may be questionable.