Not exactly a question, but I think I know why things like Red Ring and Parasitic Gene Flow aren't dropping like candy, despite the huge boosts they should be getting from HBR.
From what I can tell, the math works like this: The DAR boost MULTIPLIES the rare drop rate instead of adding to the base RDR of an item. PGF has a roughly 1.6 percent chance of dropping from Olga Flow. With a 190% boost to DAR, the odds of getting PGF go from 1.6 to 1.744 because the math is 1.6 x 1.09. PGF is popping more because a lot more people are killing Olga than usual, which is going to naturally increase the odds of it dropping for anyone, especially since the game rolls for individual people instead of a group.
The math for RR goes 0.5 x (DAR boost), so the odds after a team with a DAR of 190% beats Dark Falz is 0.545.
For Redria Lavis Cannon, the math is 4.7 x (DAR boost), so the odds after a team with a DAR of 190% kills a Red Slime is 5.1.
Basically, this HBR has far less of effect for things like RR dropping than people think. RR and PGF are dropping because more people are playing TTF and RT, particularly hardcore players and their increased RDR odds. This will inject more RRs and PGFs into the player base than a small RDR increase ever could just through sheer numbers.
For a practical summary of how HBR works, look at the D-Photon Core: if it were additive, we should be swimming in D-Photon Cores because of its inherently high drop rate (for a rare item) being added to even more with an additive RDR boost, but we're not. D-Photon Cores aren't flooding the streets because not enough people are beating OF with IDs that drop it, not because of the RDR rate boost from HBR, like with RR and PGF.