I don't really think that's as helpful, since there are two environments a projector is used. One is a batcave, where contrast ratio is very important, and lumens, less so. The other is a typical living room environment, where lumens is quite a bit more important than contrast ratio. Expressing performance as a product of the two loses all ability to gauge a projector's performance in your particular environment. Throw in other environmental differences such as the gain and size of the screen, and having seperate numbers for contrast and lumens to gauge performance becomes even more important. There is a point where more brightness doesn't really help in a batcave, and there is a point where more contrast doesn't really help in ambient light environments. Good idea when you don't consider the context... but it seems to me that we still need two numbers.