For what it's worth. . my newly acquired G4 with Phase-2 already loaded runs circles around my older G5 (acquired mid-2016- not yet P2 capable) even on Phase-1 systems, in terms of performance. Now, there could be other variables at play. . and in all fairness my G5 is on an ancient firmware (R11P from mid 2017).
But here are the noteworthy subjective improvements I see w/ the my P2-enabled G4 based on my limited observations so far:
-Issue of frequent 'out of range' is resolved in my basement, on a distant P1 system. (using same antennas, same conditions)
-Missed transmissions issue seems to be fixed! This was noticeable especially on short-replies. Not an issue now based on my non-scientific observations these past 18 hours.
-Improved speech quality. . less 'digitized' sounding.
I have sent my G5 in for the upgrade. . will be especially anxious to see if after the update it compares to my new G4. I suspect it will, and I suspect the new firmware fixes a few nuisance issues.
As an update, I received my updated G5 from Unication yesterday, and it behaves like a whole new radio with this new firmware and vocoder. . the positive observations I noted above about my newly purchased G4 with P2 are now observable with my updated G5 also. P2 capability aside, I also see benefits on P1 with the new firmware.