No DJI documentation. Only a test by Osita among his more technical friends who compared them for him. The conclusion was that the original round lens is marginally better, to an unnoticeable degree, but the FOV is slightly wider than on the elliptical lens. Conclusion: no difference, unless you want the mildly larger FOV.
Thanks. I agree that there's probably no significant difference between the two versions. But that single undocumented test wasn't very persuasive. There was only one drone of each type evaluated. Just one data point.