This is from BeHardware:
"BenQ pulled off an amazing trick. At the CeBit they unveiled a technology called BFI, which stands for Black Frame Insertion. As its name implies, the principle relies on the insertion of a black frame between two colored images to reduce the afterglow due to retinal persistence. The surprise is that this isn't what has been implemented in the BenQ monitor. Our tests (and first of all our eyes), are proof that the technology introduced to the FP241WZ looks very much like a sort of MPA (Motion Picture Acceleration), unveiled by Samsung at the last CeBIT. These two technologies are quite different.
First of all, the BFI denomination isn't really common knowledge yet. In announcements to the general public, BenQ prefers to call it AMA-Z. AMA for them simply corresponds to the overdrive. The Z indicates that the BFI has been implemented. This AMA-Z (in fact the BFI only) is available via the OSD and can be activated on three different levels (0, 1, 2 and 3).The higher it is, the more important the afterglow correction (we will come back on this point later on).
And is it a 100 or 120 Hz? There is some confusion in this area due to documents provided by BenQ. We have to point out that they haven't written anywhere that the monitor works with a frequency of 100 or 120 Hz. The misunderstanding comes from a significant imprecision in the manufacturer’s data sheet. BenQ described the BFI as a mode with 60 frames per second with black frames inserted each time. We could come to the hasty conclusion that the monitor “artificially” increases the frequency from 60 to 120 Hz. This figure would simply represent the alternance between color and black frames. However, this isn't what is happening at all. BenQ doesn't insert a black screen, but rather BFI consists of integrating an artificial screening by successively shutting down the 16 neons located in the back of the panel. It doesn't mean that the monitor is less interesting, but only that the approach and principle are completely different. The BenQ FP241WZ is the first LCD with a screening like we used to have on CRTs. Now the question is: will it have the same reaction time?"
The Benq's use a better screen than the Dell or Samsung (both the same screen) which should produce less ghosting and better color reproduction. I haven't seen enough reviews yet to determine if the extra $100+ for the (Z) model is worth it.