As for the pressure drop through the filter, I think it's insignificant, else your filter is clogged.
What Dr. John meant is that if you alter the relative sizes of any of the lines or get a restriction in any of them, from a twist or partial collapse in the line, or buildup of gumpucky, the whole system starts misbehaving.
For example, if the darin line is restricted, or the crankcase is pumping more oil than it can handle, oil can back up in that backbone, in which case the pickup is more likely to be exposed, and if it backs up enough, oil will flow out the line to atmosphere (to the airbox in this case). I've seen this latter scenario on my big-bore LM 1000. It was circulating far more oil through the backbone than the wee, dual drain lines back to the sump could accomodate that the backbone would fill up and then gush oil out the atmosperic line. It did this only at 90-plus-mph speeds.
The flickering-light problem could well be oil starvation. It could be something else, though, and your never gonna solve it until you know which it is. You guys have the tools in hand to figure this out. I don't have one of these bikes, so someone else is gonna have to do it.
As for oil consumption, that's solvable too, though the problem may not be the same in every case.