SportTracks uses the data recorded from the unit just like connect does, it just smoothes it differently. IMO SportTracks has N overly agressive default setting.
Right, but the correction he's asking about is a case when SportTracks doesn't trust the data recorded by the unit, and goes to other sources. It's not smoothing; it's looking up the "correct" altitude from the lat/lon coordinates. Just like when you tell it to look up the weather.
Altitude is the least precise measurement a GPS can provide.