It all really depends on how you execute the flare. A helicopter will have the shortest ldg distance, using a 90deg approach angle. The flatter your approach angle, the longer the ldg distance. But; you also have to consider the flare itself. A flatter app angle might enable you to go below PAPI and just "fly it onto the runway", thus achieving an early touchdown point. With spoilers, max braking and thrust reverse activated earlier, your ldg distance will decrease. However, the AOM does not have any graphs or tables for this, so you'd really be on your own ("they called it pilot error") if something happens...
I guess what I'm really trying to say is that it's the touchdown point and touchdown speed that determine your actual landing distance, and that this depends on technique. I fly the Dash-8, and with a 800m runway, 4.5 - 6deg PLASI and slippery runway, I can understand those who go below the PLASI and move their aimpoint closer to the beginning of the runway. It's too easy to mess up the flare and suddenly have a lot of unusable runway behind you.