dang, old question but I have played both, albeit not at the same time. i owned a PCG100 several years back.
you would think the racquets are fairly similar, but that was not my experience. the PCG is a very traditional racquet, whereas the GPro is a modern take on a traditional racquet. the PCG has a heavier static weight, but it isnt polarized at all. meanwhile the GPro weighs 315 g unstrung but has a 330-340 SW.
i hit a more “modern” topspin forehand with a not-quite-full western grip. BH is two-handed topspin. I dont have a real slice BH, just a chip and dropper when needed. for me, the GPro hit a MUCH meaner ball. the PCG always produced a fairly anemic ball for me, no matter which strings I used. meanwhile, provided I wasnt tired, i could really clobber the ball with the GPro.
long story short, I found the GPro superior in all respects. but thats due to the way i play. if you are used to the way the PCG plays and have more traditional flat strokes, you might hate it.