is the 2ms monitor 120hz? if it is and you get more than 60fps consistantly then yes maybe it is worth spending extra. if all you gain is 2ms over 5ms then no its not as big of an issue.
if you buy a cheaper monitor with led backlighting they can have a blue-white or purplish hue due to the type of leds used. more expensive monitors use white leds so there is no issue. ccfl also does not have this issue. led backlighting will save you a bit of money on your power bill over ccfl but does not offer any visual quality gains or contrast gains at this time. if they ever bring a grid array led backlighting schema to monitors then there could be better contrast due to zone backlight control but at this time i think this exists in high end televisions only.
visually speaking both should look about the same. if you want to make the game look clearer, more vibrant or have better color there are other things to consider besides response times.
Generally, people cannot tell the difference between 5ms and 2ms. "LED monitors" are simply LCD monitor with LED backlight instead of the traditional florescent (CCFL) backlight. LED consumes less electricity and since the are very small the LED lights are around the edges of the LCD monitor ( commonly referred to as edge lit) as opposed to "full array" for CCFL backlight which is directly behind the LCD panel. This means LED backlit LCD monitors are thinner lighter and consumes less electricity.
LED backlight is not truly white. Blue LEDs are used with a yellow phosphorus coating to imitate white. The vast majority of times this works well, other small percentage of times people may notice a colors have a slight bluish tint.
Many people seem to like glossy screen LCD monitors because it makes colors "pop". However, you need to deal with reflections.
2ms response time would be most critical for 3D. That response time will cause crosstalk and ghosting. While this might not be all that apparent for most uses, in 3D, that ghosting is extremely visible.