Nope, it cant (be quantified - I can not at least)
But you can ride in less wind, and have a more direct feel even with really long lines, so thats the deal, no matter how small the difference is.
I am not to say if I can feel it or not, but one day I CAN say, when I have made a bar with thinner lines and comparing on the same day, if I can feel it or not...
Somewhat just like a lighter board and foil feels and works SO much better in every way, a huge difference.
It can not be quantified either (apart from the weight diff) - but really easy to feel a major difference when riding, in every aspect
Also, even our normal thick and strong rear lines at least, seems "stupid" for hydrofoiling, if less than half is more than sufficient, especially as it is two different bars anyways and you need new lines for hydrofoiling in marginal winds, so why not choose what is more spot on meaning thinner but still good overhead