I know this is an old thread, but thought I'd throw in my $.02. I've had an Acurite 5-in-1 for about 8 months now and I just bought the Davis Vantage Vue about a month ago. They are both mounted on the same pole, but the davis is about 3 feet higher than the Acurite. I've noticed that sometimes they are exactly the same and others they times they are off by up to 5 degrees. For example, right now we're are at the tail end of a snowstorm here in MN, so it's overcast the snow has ended and there's a light wind.
Davis Vantage Vue:
Temp: 28.2
Dew Point: 25.1
Acurite 5-in-1
Temp: 33
Dew Point: 30.1
There are 2 other Davis stations, another Vantage Vue and an Pro 2 near me that are reporting 27 to Weather Underground.
Both are in full sun and I upgraded the Acurite to have the Pro anemometer so it has the dual solar panel for more accurate temps. The fan is starting to sound sick though, you can hear it making noise so I don't know how long it's going to last. From what I've noticed so far, the Acurite seems to fluctuate in it's temps more than the Davis. But they are pretty close most of the time.
What did it for me was when we had a week of record low temps here at the end of January and I look at my Acurite console and it said it was -6 (for the high temp for the day), whereas on Weather Underground most others in the area were reporting -15 so that was the last straw for me. I'm also thinking of modding the Davis to add a fan aspirated radiation shield maybe when all this snow melts.
Anyway, just thought I'd throw that in there.