Does the scaffold symbolically represent good (repentence) or evil (public humiliation) in "The Scarlet Letter"?

A case, as usual, can be made for both sides, but overall the novel suggests that the scaffold is a positive place.  Let's start at the end, and work backward.

Dimmesdale suffers throughout the novel.  He becomes a shell of his former self, his guilt manifesting in his outward appearance through his shrunken appearance and in the A that becomes etched on his chest.  At the end of the novel, with physical escape a near possibility, Dimmesdale chooses spiritual escape through repentance.  He climbs the scaffold and confesses.  Although he dies afterward, he dies at peace, united with Hester and Pearl and accepted by Pearl as his father.  It is a positive end for him.

A spell was broken. The great scene of grief, in which the wild infant bore a part, had developed all her sympathies; and as her tears fell upon her father's cheek, they were the pledge that she would grow up amid human joy and sorrow, nor for ever do battle with the world, but be a woman in it.

The scaffold scene before this is when the three of them are upon the scaffold at night.  This is when Dimmesdale is considering his own guilt.  The group is family unit upon the scaffold and large A appears in the sky.  Although Dimmesdale sees it as a sign of his guilt, the town sees it as a sign of an Angel, giving a positive connotation to both the family unit and the scaffold itself.

Before this event is when Hester is upon the scaffold after her imprisonment.  Although it is a moment of public humiliation for her, it is also an opportunity for her to make a stand.  She refuses to reveal Dimmesdale as her lover, and shows her steadfastness and integrity.  Hawthorne establishes her for us as a strong and resilient woman, and Hester proves to the town that she is capable.

Public humiliation is an aspect of this novel, but it is present much more in the symbol of the letter "A".  It is the letter that causes the young children of the town to follow Hester and throw rocks.  It is the letter that weighs upon Hester, causing its own physical manifestations.  When she takes it off, her whole visage appears lighter and more free, proving that it is a negative effect upon her.  The letter had

"the effect of a spell, taking [Hester] out of the ordinary relations with humanity, and enclosing her in a sphere by herself.”