There are some reports of the Samsung P2450 having pretty off colours by default (so requiring a little bit of rebalancing) and (this may not matter) not offering proper progressive scan over HDMI for use on the PS3. I don't know a lot about the E2472HDD other than it's Iiyama's first LED backlit panel that offers decent performance for the price (although arguably the BenQ G2420HDBL may be a better bet).
LED backlighting can have certain advantages such as increased luminance over the same panel with CCFL ('standard') backlighting and less flicker on whites and light shades (the latter is not something most people will even notice to be honest). It also makes the monitor thinner, lighter and more energy efficient. LED backlights can also be controlled very precisely - the reason that the Iiyama's 'dyanamic contrast ratio' is higher is that the figure reflects the ratio of the white (where the LED backlight can be fully on and very bright) vs. a seperate scene showing only black (where the backlight can be effectively off).
In short the dynamic contrast figure makes little difference in reality; what matters is the static contrast ratio, as this tells you a little bit about how deep blacks should be and how brights whites (as an indication of any colour shade) should be in any given scene. In both cases this is stated as 1000:1. As for the luminance - I doubt the Iiyama is less bright than the Samsung given the difference in backlighting. It could well be, but I have tested several LED backlit and CCFL backlit panels and in all cases the 'typical luminance' can be exceeded if you want a really bright image with the LED backlighting offering superior peak luminance. Manufacturers measure this and consider 'typical' in different ways, so again this can be safely ignored.
