I understand the desire to experiment with warm whites, but as an FYI, NW's (which are I believe ~2000k higher than WW's) are VERY yellow. Some of the guys on nano reef experimented with WW's and attempted to balance them out with RB's/B's, and the outcome was "Wonka-like" (not in a good way). I'm never one to discourage experimentation, but I don't think going much lower on the Kelvin scale than NW's will be very aesthetically pleasing.
The key to adding reds (which many people scrapped) seems to be driving them at a lower current (not sure if this is the right terminology). Essentially, running even one LED at the same intensity as the other LEDs in the array was enough to give a terrible "disco-ball" look...think red bouncing all over the sand from the shimmer. I have, however, seen a few builds where a 1W red was added (amongst 3W LEDs), and the effect worked. All this to say that I also had the problems with red/yellow color pop, and it was instantly cured by replacing a few royal blues with blues.
See this post for some other clarification on mixing whites:
http://www.nano-reef.com/forums/index.php?s=&showtopic=246394&view=findpost&p=3314433