Well, I've had my airplane flying 11 MPH backward, according the GPS groundspeed (It was a windy day), so with that in mind, I'll continue to use the airpseed indicator for airspeed information.
I do remember test flying a Tiger Moth following maintenance. It had three airspeed indicators, one in each cockpit, and a vane device on the wing strut. They all differed by about 10 MPH to each other, so I ignored them all, and just flew by feel, it was fine. In hindsight, I think the vane on the wing seemed the most accurate.
I really like the GPS for pointing me home, and telling me when I should expect to be there.