First off, I searched and didn't find the answer, so if this is a commonly asked question, please forgive me. I'm going to be purchasing a Phantom drone to do inspections on roofs (My company specializes in hail restoration on residential and commercial structures). My intention is to use the drone in places that I don't want to climb, such as steep pitches or 3+ story apartment buildings. I am currently going through the FAA legal hoops to obtain the Feds permission to fly it for business. I'm torn between the Phantom 3 Pro and the Phantom 4. I have zero use for tap to fly and active tracking, but the obstacle avoidance on the 4 has me thinking. It would be great if I could fly the drone close enough to a roof to see damage to shingles, but at the same time keep me from smashing into a customer's building. Will obstacle avoidance allow me to get close enough to do this while still providing protection from crashing, or will it just prevent me from getting close enough to get a proper view of the roof components? I see the obstacle avoidance range is adjustable, but I'm not sure what that means exactly in terms of how the drone behaves when it comes upon an obstacle. Thanks in advance!