53x12, I mentioned the setup in regards to the selling point of being able to quickly and easily swap the pedals back and forth between bikes just like standard pedals. I have not installed vectors myself, but after reading Ray at DC Rainmaker's review and a few others, it takes much longer to set them up properly (when moving between bikes) than a simple pedal swap typically would. If you're simply installing them once, I would agree with you - it's probably just as much or even less time than installing a crank based system.
In regards to the price, I was initially excited when they were proposed to be launched at $1200. At $1700, there are a few crank based options for that or less, and a PT is considerably less.
I think even DCRainmaker would agree the first time he installed them he didn't take the time to do it correctly. After he noticed the issue and installed them the right way there was no issue. I would agree that the time difference between swapping pedals and crank/crank arm is minimal if any.
The benefit of the Garmin is for those that have multiple bikes that have different cranks (BB30, BSA...etc.) and different wheels (training and racing). I am one of those as I have several wheels I use (no PT for me) and I have several bikes with different cranks (no Stages/Quarq/SRM). Garmin is the only viable option for me to make me happy. Plus all the cool analysis options that Garmin will soon incorporate.
Another benefit is for those that travel frequently and either rent or borrow a bike on their trip. Want power during your trip? Just throw on your Garmin pedals. Easy peasy.