about to purchase a flash for my nikon d40...im between two. 1. Nikon Sb-400 2. Bower SFD35N i have heard raves about the bower, even on B&Hs website there are 10 lovely reviews on it! that one is priced at $70 and many reviews compare it to be nearly up to par as the Sb-600! the sb-400 also has great reviews, and i am willing to spend the $110 for it, however, the only thing that is drawing me away from it is its inability to rotate (330 degrees or 270 for example, meaning i cannot bounce it off the ceiling when i am taking vertical portrait shots) suggestions on what would be my better option....also, what is the difference between TTL and i-TTL?!