I think the stiffer thigh rise is great. Like you, I was a little concerned about how stiff they would be. It's why I went from a 33+2 V9 to a 32+2.5 PX3. They still have great flexibility in the boot and below the knee (mind you, this can be specced differently, I ordered the flexible options for both).
It took barely any adjusting at all, and I think the thinner thigh rise will actually be less of an adjustment than going Eflex to 12.2 because there is VERY little interference in the thigh rise.
Goalie pads in recent years have really pushed the envelope on thigh rise stiffness and pad seal. There's no question I lost a tiny bit of mobility compared to my V9s (although sizing down 0.5" helped), but I'm not worried about my pads trap door-ing a five hole goal.
Another thing to mention, these pads are FANTASTIC with butterfly movements...the weave slides better than my Vaughns with quick slide.