In the forum you can found a lot of threads about that .
I tried with Freetrack + webcam + white leds lights , my result = failed , but a lot of people said it's work perfectly.
If you are sure of the buy... buy G25, but if you want some playings and some time buy DFP, I have a G25 and a DFP, G25 is other world... but DFP are good for newbie, but it's make a horrible sound in the cournes.