The old color setting in the new clients doesn't actually use the old colors exactly.

This is the output of /color in an MCForge server using World of Minecraft 1.6.6:

http://i.imgur.com/90UEx.png

This is the output of /color using World of Minecraft 1.8.5, using /client colors old:

http://i.imgur.com/7aXcJ.png

I also sampled the colors in Paint.NET, and these are the hex values for the colors:

• Navy. 1.6.6: 0000BF, 1.8.5: 0000DF
• Green. 1.6.6: 00BF00, 1.8.5: 00DF00
• Teal. 1.6.6: 00BFBF, 1.8.5: 00DFDF
• Maroon. 1.6.6: BF0000, 1.8.5: DF0000
• Purple. 1.6.6: BF00BF, 1.8.5: DF00DF
• Gold. 1.6.6: BFBF00, 1.8.5: DFDF00
• Silver. 1.6.6: BFBFBF, 1.8.5: DFDFDF
• Gray. 1.6.6: 404040, 1.8.5: 202020
• Blue. 1.6.6: 4040FF, 1.8.5: 2020FF
• Lime. 1.6.6: 40FF40, 1.8.5: 20FF20
• Aqua. 1.6.6: 40FFFF, 1.8.5: 20FFFF
• Red. 1.6.6: FF4040, 1.8.5:  FF2020
• Pink. 1.6.6: FF40FF, 1.8.5: FF20FF
• Yellow. 1.6.6: FFFF40, 1.8.5: FFFF20
• White and black are the same in both.

The other difference you can see between 1.6.6 and 1.8.5 is that the drop shadow in 1.6.6 changes color based on the color being used. I would really appreciate it if a future update let us go back to the 1.6.6 text in every way. And if the differences I'm seeing are because I'm doing something wrong, please let me know!