Rec2020 for Print workflow, any obvious downsides?

[repro_glenn]

https://printplanet.com/threads/using-eci-rgbv2-instead-of-adobergb.15218/

this discussion from 2011 proposes Export from Lightroom as ProPhoto RGB then convert to ECI-RGBv2 then retouch. ECI-RGBv2 gets to most of a wide format inkjet gamut, presumably this makes it a better choice than either Adobe RGB or one of the P3 spaces.

Is there an obvious downside to using Rec2020, since it would appear to cover both Adobe RGB and P3, and unlike ECI-RGBv2 doesn't require an extra conversion in Photoshop.