A bike forum? You didn't really think anyone needed the reminder, did you?

The topic is GPS accuracy in general, and one of the sub-topics is GPS alone vs sensor-based speed and distance accuracy. My own few observations tell me sensor-based reporting is more accurate than GPS alone. That's based on 3 GPSes - 2 phones and one Lezyne GPS unit. I didn't do extensive testing, because the first few tests with each were so telling.

One poster states categorically that GPSes are more accurate. I have no doubt that it's true under certain circumstances, but it's just not true under all conditions, so the statement is false. It's an over-generalization.

A GPS may sometimes be more accurate than a sensor-based system. Sometimes it's less accurate. If you know the conditions in which you ride, you have a good chance of picking the method that will be more accurate. If you don't have that knowledge, you'll probably get more accuracy from a wired, sensor-based system than from a wireless sensor or a naked GPS.

It matters not what package the GPS comes in ... but don't forget that many cyclists rely on their phones for GPS services.