The BenQ W7500 surprised me. I generally expect DLP projectors to turn in really excellent lag times. I haven't seen an LCD Projector or an LCoS one, that normally comes close to what most DLP projectors can do.
Thus when I measured 51 ms lag time agains my MacBook Pro, I was surprised, I had really expected mid-30s at worst, and perhaps a lot better.
I tried. Some features, especially creative ones that look ahead to the next frame, can quickly slow down the speed. I went through menus by menu, turning off everything in site. FI (frame interpolation) 3D Auto, even Gamma was set to it's default, I tried Brilliant Color both on and off. I even turned off the dynamic iris.
The speed never budged, none of those controls had any impact. One feature that one can turn off that yields a reduction on some other brands of projectors, is shutting off Deep Color (basically color depth greater than 24 bit (16.7 million colors). That's a small price to pay for a a serious gaming projector.
So the bottom line here is that the BenQ is right there at 50 ms. That's virtually identical to the Epson 5030UB, and 4030. Therefore, I'll say exactly the same thing:
It would seem that the general consensus is that 50 ms is acceptable to many serious gamers. By 80 ms, many are really starting to notice the lag. It would be better if the BenQ was in the mid-30's or half of that. Still, it's fine for everyone but the really hardcore gamers that are particularly sensitive to longer lag times. There will definitely be some folks who will find the BenQ's 50ms range time to be too slow, but that should not be very many people.