LED driver board interchangable with pre-Unibody MBP?

I doubt replacing things here will improve things. The oscillation of the backlight LED's across all of the systems is the same (no difference in the circuit design). While the intensity is higher the flicker is less when you have the display at full brightness

CFL backlit displays are in fact a little less harsh as they have enough afterglow to smooth out the harshness when at full brightness.

Have you spoken to your Ophthalmologist or Ophthalmic medical practitioner? Heres some info on Photophobia. I my self suffer from it (I have light blue eyes) and I wear tinted glasses with an antiglare coating. It made a big difference as I need to stare at a screen most of the day. Don't forget to work in a well lit area with indirect lighting so you don't get the glare (no bare or vented bulbs shining at you). And lastly, have the wall behind your display a mid brightness color (light brown). White or brightly colored walls make things worse and busy prints or large different colored patterns also don't help (even color).