Ben,
Your a scientist, there are calculations on drag coefficient that clearly show an item in water has considerably more drag than when in air.
It is beyond arguement that if you are sitting low in the water you will be less effected by wind than if you sit high in the water.
HOWEVER, by sitting higher in the water, you have less drag beneath the surface, so, given certain conditions, it would be easier to paddle against the wind than if more of your body is in the water.
What this means is that a tube like a Shakey will drift less in the wind, but a tube like your Guideline will be easier to paddle about...up to a certain point.
There are things like Boundry Layers, Hydrodynamics, Adverse Pressure Gradients and Vortex's etc that affect things too...but they hurt my head!
As a note...the chaps I know up in Inverness that have Guidelines for their Pike fly fishing have drogues to slow them down in the big winds.