Having had the surgery done on both heels (by, alas, two different doctors), my understanding is that how much bump remains after surgery is a matter of how much bone is removed.
Here's my general advice (quoted from an earlier post):
Make terribly certain that you find a doctor who (1) has previous experience with performing the surgery and (2) has performed it on runners, and so chooses his options with a view to a runner's higher-than-average performance expectations. It might even be good, too, if you can find a doctor who is also athletic ( --a good piece in the NY Times a month or so ago discusses this point).
I curse myself every hour of the day for making the fateful mistake last May of trusting a doctor who cut out far more bone than we had agreed upon, detached some of my tendon from the bone (which I expressly and repeatedly forbade him to do), and left me helpless and hostage to his ego until my desperation grew to the point where, thanks to the sympathetic presence of an athletic resident physician, I finally obtained a referral to someone else (whom, alas, I won't be able to see until late March). I was running 95/week up until the day before the surgery, intended merely to have the extra bone shaved off and, as was the case with my other heel (for which the surgery was done by another doctor almost exactly two years before), be back running by 12 weeks. Now I fear I've been crippled. How I wish I'd simply gone back to the first doctor!
(Anyone considering getting Haglund's Deformity surgery in Lexington, Kentucky should contact me: I've had each foot done by each of the two doctors in the Lexington area who perform the surgery, and I can tell you which one is an athlete's worst nightmare.)