Mostly getting the battery weight in line with the props ( thrust plane) . Most people trying to achieve this use a top mount battery, but that requires a super slammed stack and a more difficult build. This will achieve better overall feel and response due to better mass centralization on z axiz.

Other pros to this setup is no blocked thrust from it hitting the arms and causing turblence, the fpv camera will stay cleaner, and less chance of damaging motor since they are "behind" the arms in a forward flight impact. Also less/no motors in fpv camera view.

Very interesting. So you just land on the battery? Or do you flip 180 degrees before landing?

I just land on the battery/ props. I usually disarm 2-3 feet above the ground and drop into grass anyway. These things are so tough, you need not worry about it.

Cool!

I haven't flown it enough to tell. Im not a super serious racer, im still a novice. I can see that they would be slightly lower while going through gates. I may reverse the prop rotation to try and lower that chance of getting "sucked in" to tall grass.