I don't adopt this approach quite yet. For one, mixing in Atmos is young still, certainly not as mature as 5.1. In my opinion, for example, The Future Bites is better in 5.1 than Atmos. Second, there is a resolution limitation. I'm not one of "those" audiophiles who believes everything has to be 96kHz, but I can tell the difference on some of the mixes.
I think it's important to listen to both and make a decision on which you prefer, as it's not so obvious that Atmos is automatically "better".
That said, I do prefer the Atmos mix of The Tipping Point.