What makes this time better than any other? Seerah is about the life of Rasoolullah sallallahu alayhi wasallam, not merely his (saw) birth! Again, it's apples and oranges. the practices of Tasawwuf are a means to the end of spiritual purification. Where they are not derived from the Sunnah, then they are arrived at through a sound knowledge of which means are most effective to reach this end. On the other hand, there is no evidence which suggests that studying Seerah in the month of Rabi-ul-Awwal somehow inculcates the love of Rasoolullah sallallahu alayhi wasallam more than studying it in any other month. Put this way, such a notion seems laughable, no?