P1 user here. Swapping between bikes is simple/fast. Have not experienced spikes/drops w/ power or cadence. Just spin the pedals, zero out (calibrate) on the Garmin and off I go. I do get the right power meter missing message from time to time, but all measurements including right/left balance is visible and downloads. Just waiting for Garmin to update 920 & 520 firmware to allow crank length adjustment.
I’m happy with the purchase.