I have installed LED's as well, in the dash setup (Sports dash).
I used all different colours and brightness's.
The one thing I found with LED's is that they have only about 10 ° of viewing angle. There is a part of the dash (the insides) that stops the light from directly hitting the dash display, rather it disperse's light from the sides (little cutouts on the insides), this creates the subtle lighting. The incandesant lights can disperse this light, where as LED's can't, you either have to get LED's that disperse light at over 45 ° or get brighter wattage bulbs, but that creates heat.
Have used all the way from 2,000 mcd to 10,000 mcd. I like the blue tone (like artic blue colour), that was at 8,000mcd, but it was still too dark to make the display legible to read. The actual display material doesn't help either.
I think the white display material and LED's would be better, but I haven't done this yet. But I think I have to work on the way the light is dispersed with the LED's, workout someway to help it being subtle, but yet effective.