This is something that never really occurred to me until recently, and I'm afraid I've probably suggested to many people that they use $posts['post'] as an integer. In any case, I don't think there's any way to use that value in a conditional. What you could do is create a plugin using hook postbit_display_start and save the value to another name, like maybe:
Code:
$post['numposts'] = $post['posts'];
The of course you'd use $posts['numposts'] in your template conditional.