bare in mind that this Faroudja image processing was not use in the GM1601 Genesis chip in the 2405FPW
It's one of those things which in theory is useful, but many screens are perfectly fine without it. The 2407WFP in it's A01 "desktop" setting is fine, and you don't really notice the loss of the Faroudja algorithms. These enhancements are commonly used in LCD TV's, maybe it's designed more for that application, but was tacked on to the Genesis chip for the 2407WFP as it was being more geared up for TV use as well, with its HDCP support. It's not needed, the screen is perfectly fine without it.
I think on larger LCD TV's, the ACM and ACC features are useful since the screens are more aimed at movies / Tv / games. The Faroudja processing might help in these cases as the suite of enhancements is really designed to bring the most out of movies and film on displays (improve brightness, improve minor movie details, improve jaggedness etc). However, on the 2407WFP, in "desktop" use, you don't need these enhancements since you're using static images and Windows use. Dell have left the processing enabled in the other presets like "multimedia" and "gaming" so that you can make the most of these algorithms for these other uses. The technology was designed for multimedia / movie / gaming use, so Dell have left it enabled. In the two presets you can see if the Faroudja processing makes any difference, but i would imagine you can get just as much out of the screen by leaving it in "desktop" mode. The techology is designed to tweak display characteristics for multimedia use, and might well be very handy for TV's. However, PC displays are far more customisable by their nature as you have a massive control over them not only through the OSD, but from your graphics card as well. Having a chip in the monitor tweak the display settings in movie playback for instance is just not needed since you can tweak things yourself through software etc. Hope this makes sense.
What I'm trying to get at is that LCD TV's are not as easy to tweak yourself, and are pretty much exclusively used for multimedia movie and gaming purposes. The suite of enhancements in the Faroudja Video Processing technolgoy are useful to help get the most out of the screen in these circumstances. On a desktop PC display, you use it far more for static images and windows, and you don't need these enhancements anyway. If you do use the TFT for multimedia, you can use software and graphics card / monitor options to change things anyway. For those who don't want to have to tweak the settings themselves (if they even needed to) they can just use the monitor presets to allow the Faroudja processing to operate, just like it would if it were a multimedia screen anyway. I think Dell have made a good move really here, allowing the user to choose how they want to use it. In practice, for a desktop TFT, i doubt you would ever need to leave the "desktop" preset mode.