The results are interesting, thanks for posting them. Now, in real world I don't know if the degradation would be apparent. Sharpening and other operations could lessen the perceived effect of lens corrections.
Yes I think you are right. I have updated the page with the effect of sharpening and a real world example that was sharpened before correction but not after.
The real world example shows almost no loss but then it was only a hand held shot.
I guess this makes me a little less worried about this problem.
PS I have also uploaded one of the test patterns so you can try this on PTLens if you want.