Guys,
This is my personal strategy/opinion when it comes to calipers... When you really want to measure something, use an appropriate micrometer. I use calipers all the time but not for anything critical. I have one Mity from eBay and several Harbor Freight in various sizes. They all give about the same readings and they all eat batteries regardless if they're turned on or off -and it's way too much hassle to keep removing the battery. For what I paid for the Mity, I bought all three of the HF units -and like I said, they all give about the same readings -none of which I trust as much as reading with a traditional micrometer.
I think calipers are fine for quick readings. At one place I worked, the calipers had a serial cable connected to a computer so we could log the results of incoming QC inspections. Basically, I view them as medium longevity devices. Two of my oldest ones are about 4-5 years old and one is starting to act weird. For the 20 bucks they cost, I consider them to have served me well...
Ray