Something else here to consider is the difference between the machines themselves. I own and fly both the H520 and the Inspire 1 V2. I do NOT have theremal cameras, like many of you I am reading and waiting to see. Back to the machines themselves
Overall the battery duration is much better on the H520 than on the Inspire 1. Secondly, I personally find that slow motion, fine control on the H520 is better / easier than the Inspire. Last, regardless of what anyone says, the idea of 6 props vs 4 in some situaiton puts my mind at a bit of ease. If you want to chase race cars around the track and get great cinematic footage, go Inspire, but for mapping and inspection, the H520 more and more is the machine of my choice.
I guess the best way to describe the issue to people is flying DJI is like a sports car with a big V8, and flying the H520 is like a pickup truck with a big turbo diesel V8, if that makes any sense.
Another factor is cost. DJI is no longer making the Phantom 4, they are pushing the Mavic instead. While the Mavic is fine for real estate and wedding work in low winds, it's not useful for much else. So there is a real gap there betweent he Mavic and the Inspire which the H520 fills in both size and performance. For example, I find that I use my H520 far more than my Inspire 1. I suspect that to find a machine equivalent or better than the H520, I would need ot go to an Inspire 2. However, at least here in Canada, when I priced everything out, a full Inspire 2 package was lmost twice the price of a similar H520 package. I looked at other machines and packages too, but then the price jumped considerably. Beautiful equipment, but not cheap. Depends on your needs. For example, if you want to shoot footage for the next Netflix movie, and Inspire 2 with a top end camera is the way to go.
So at the end of the day while you can find better machines than the H520, the price will be considerably higher. At this point, that is a major consideration.