I don't think its a good idea personally, there are a lot of colorspaces out there and we probably don't want to clutter our ColorRGBA class with all that. I think a better idea would be to have a ColorspaceUtils class that can convert between all those color spaces.
That's exactly what I did in my project 
Just wanted to share the code in case anyone whould need it
For lots of image and color space handling code you can check ImageJ project: http://rsbweb.nih.gov/ij/.