Before you drop coin on a multi-color LED flashlight, test your theory and optics with $1 blue and red LEDS from countycomm - see
http://www.countycomm.com/light10.htm. $2 + shipping/handling (plus whatever else you can't resist on countycomm) should give you an idea what you can see and what you can't under blue or red light. I'm not sure where to get green or yellow LEDs but hopefully they aren't far off in price. I did see some somewhere, probably the same place they stock black light LEDs for following blood and rodent trails etc.
I also bought a cheap red light filter on lighthound.com that slides on over the end of a Fenix model Cree LED light - not sure if they have other colors but the red light is pretty good for preserving my night vision. They have these
http://www.lighthound.com/index.asp?PageAction=VIEWPROD&ProdID=3523, RedBlueGreenYellowOrange sized for something called a PentagonLite, (I suspect they refer to a 90 angle head light like they carry at CountyComm), but for $16 you could try them on your LED light and at least try the different color spectrums.