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I think single side is perfectly fine for pretty much everybody. Dual info has been interesting when I've been working through injuries but very rarely outside of 45/55, which is the point where I'm told it becomes significant. Consistency trumps everything.
The P1s can be swapped in 30s and don't need any calibrating, so they're ready to go for every single ride, including rentals if I'm away travelling. For ultra-distance rides it's also handy that they take AAA batteries, which I can buy anywhere if I need to.
I've had mine for about 3 years. They've been replaced 2-3 times after failures. No quibbles but it does take a few weeks each time. Annoyingly the failures all seem to happen right at the start of my biggest events. I stick with them because I'm too tight to buy multiple power meters and these are still the easiest solution for swapping between bikes.