From what I hear, there are usually a few SRO spots left hours after rush, even post-Tonys. According to the box office it varies every day, but certainly not all spots are gone every day by 10:30.
And also...still looking for an answer to my question above about a limit on SRO tickets...
"If there is going to be a restoration fee, there should also be a Renaissance fee, a Middle Ages fee and a Dark Ages fee. Someone must have men in the back room making up names, euphemisms for profit."
(Emanuel Azenberg)