My personal recommendation is to turn-off the 'automatic' function of the PC7. I am not convinced that the 'bugs' are out of it yet. Rather, I recommend that you manually input slope, as in previous editions. You will be guaranteed to have no problems then.
digging up an old thread, but i wonder what these referenced bugs are.
i've been using a garmin device to update the slope in multiple SRMs (it's very convenient when you discovered the slope does not match what is set at the factory--thus, you don't have to remember (a) what the slope should be and (b) to make the change before every ride.
the power meter itself can store this value and transmit it back to the head unit. before i used this method, i found that no matter how careful i was, i did not always remember to switch the slope when riding a different bike, and this resulted in some funky situations.