Neons output more of a glow and consist of one long bar. If the bar gets cracked, the whole thing will go out.
LED's are bright, but more of them are needed to get an effect (hence loads of em in a tube). If one led breaks, the rest will continue to work. Another thing about these is you can get multicoloured ones, ones that flash and other fancy features - which neons dont have.
The LED ones cost more due to these extra features and laster longing
Am told that blue is a no as it's for emergency services and that they are not meant to be facing forward.
I asked my police mate about neons he said most peole get pulled and asked to turn off but he's knows of some that would then check everything on ya car and find something!
If you do try it make sure everything else is legal.