This has left the urban myths world and ventured into the area where engineers and scientists think about the same things in different ways.
Try to forget about how to measure pressure, because that introduces so many other effects that it becomes easy to lose sight of the basic principles.
Think more about Newton's first law. Take one molecule of air moving swiftly toward the surface of the earth. It encounters ground. More molecules are charging up behind it. If you want to ease calculation and make the air incompressible, you have to increase pressure (and temperature will increase as a result). If you decide to be a realist and make the air compressible, you either increase pressure or temperature or both, however at some point you'll find you have to increase pressure. You're probably thinking that you don't need to increase pressure in either case because there is somewhere for the molecule to go, hence the pressure "spills" out. However, that molecule is going to keep going downward unless "compelled to change direction by a force impressed upon it". So we need a force that is pointed upwards (to reduce the vertical component) and outwards (to accelerate away) from the center of where the downwash strikes the surface. That force comes from the interaction with the molecules in the higher pressure area (its 3D so if you want to call it a bubble, go ahead). You can call it stagnation pressure if you like, but that is still a real pressure.
Now for the measurement. If I get a chance to do this (bjc, you in on this discussion?), then the biggest issue will be in measurement error. The differences in pressure we'll be looking for will be quite small, we will require much more precision in height than normal, and normal local variations in pressure could be greater than some of the numbers we try to measure. Or, we could discover a giant bubble of pressure (not likely).
Now for the urban myth. I haven't changed my stance. I do believe there is a pressure gradient formed underneath the hovering helicopter. It is an essential part of determining the flow of air in the vicinity of the helicopter. Also, when you move the helicopter forward, there is a sinking feeling. When you are trying to keep the helicopter still, it feels statically unstable, as though trying to balance a baseball on top of a basketball. In fact, it feels like you're hovering on a bubble. Two different facts, but I think this is where the urban myth holds to an extent. Just because the pressure "bubble" is there, doesn't mean that is why the helicopter feels like it does.
Of course, next time I describe how to hover, I still might refer to this sensation (and will caveat that it may not be scientifically accurate).
Matthew.