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Third pic in post #21, that's the trunklid during tufts testing without the airtabs on right? How do the tufts looks at the end of the trunklid? Is it just me or the flow reattaches to the trunklid? If so it's evident why you didn't get an improvement with the airtabs. If the flow reattaches without vgs, all you're doing is reducing the size of the arch vortex.
Vgs have an induced drag cost and a potential form drag benefit. They are only worth it if the form drag reduction benefit outweigh the induced drag cost. This cost/benefit ratio is highly dependent on vg design, density and placement.
My feeling, from looking at what's been demonstrated to work on airfoils is that airtabs put form over function.
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