Great report. I've had the Nano since May and just got my Shield 9 yesterday. I can't tell which is more accurate, but I will say that they are both as good as the shooter. Cannot say which I like better. It is okay to love both, right? I think you were spot on comparing the shoot from the hip. For me, I have a Hogue Jr. on the Nano and the grooves on the grip helps me get the muzzle of the gun up just a bit towards center mass.
Anyway, I think you nailed that comparison. Thanks for the report.