Dunno if this is the right place to post a forum-related question, but here goes:
From a user-point-of-view: Wouldn't it be recommendable to activate the option: 'Notify me of replies' upfront?
People who do not want to be notified of answers to their questions, well ... what the h*ll are you doing here anyway?
People who do want to be notified of answers/ solutions, don't have to make this extra step.
Seems logical to me.