I still have the IRC front which now has over 12,000 miles on with a City Grip rear.
The combination works surprisingly well.
There is much less wiggle over surface joins, white lines and the like than with the old worn IRC rear tyre.
It's difficult to compare like for like because its a good while since the IRC was new.
As it is I would have no hesitation recommending the 100/90-14 City Grip rear for the PCX.
Use the ten bucks for gas

Four decades on two wheels has taught me nothing, all advice given is guaranteed to be wrong