Ive done about 10000km over the last 12 months on Garmin Vectors. 90% has been on the west coast of Norway which means tons of wet weather riding...it doesn't get much wetter anywhere in the world from what I'm told by people here. So far the only problem I've had is that when its cold, say around 5C or less, i often get a "Power Meter Battery Low". This is meant to occur at 20% battery life. After receiving this message at the start of several (colder) rides over a month my first battery set died after about 70hours (claimed is something like 165hours). I tend to ignore the warning now as on warmer days it doesn't pop up. I have concluded that they probably do last close to the claimed run time at more "normal" riding temps but climbing up into the mountains or long base rides in November were most rides are temps between -2C and 6C for hours just kills the batteries faster.
Its a fact of life that batteries just don't like cold so this wouldn't strike me as a problem if it was normal for all power meters but my mates P2M does seems to last much longer...although he doesnt ride as much as me so maybe his is not a fair comparison.
At the end of the day batteries are cheap, they take less than 2minutes to change and i get plenty of prior warning.
I would have ordered a P2M but i wanted a Power meter for a trip to Mallorca so need it right then and there. pretty happy with the vectors all up but would like to leave the torque wrench at home when travelling with the bike...no biggie.
As for breakabilityx of the pods.... I've crashed twice and got hit by a car once. The cars bumper hit my right shoe and pedal. Myself and the bike went flying up over the front of the car and crashed down on the road on the far side of the car. Whilst my shoulder was stuffed the pods and power meters remained intact and unscathed, and still work perfectly. Worth mentioning that the other two crashes were my own fault and weren't in group rides. Ive just discovered through this thread that Team Garmin has stopped using Vectors. I wonder if the pods are more likely to break in a group crash and therefore potentially affect race pacing/strategies/outcomes ?? Regardless, Ive heard that replacement pods aren't too expensive to replace if necessary. Should a pod ever break my biggest fear would be not seeing/recording the data while training rather than the actual cost of the replacements.
If i had my chance again it would seriously consider a P2M just for the ease of traveling with the bike (not having to take the torque wrench), they're a bit cheaper for me to get in Norway and I'm willing to bet (but don't know) that they are more serviceable....oh and i always wanted to try out speed play pedals