I'm about to step on a loooooot of toes here.
If your looking at a Cree Fixture I would avoid the Neutral LEDs as they tend to be yellow looking and offer less PAR due to a reduced 450 nm Spike.
A few companies actually Bin their Cree LEDs for optimal looks. It really makes a difference in looks. As not all Royal Blue and Cool Whites are the same.
Reds, Greens and Violets do little for growth and are personal preference.
The best thing to do is see the fixture over corals and if you can compare fixtures. Most Frag Swaps have vendors with different types of LED Fixtures there you can see which ones really make a difference in colour pop.
Bill
I'd expect no less from a vendor who only sells fixtures using cool white LEDs.
Without the additional red spectrum, not only does the tank just look anemic, but you start to lose non-fluorescent colors. That's great if all you want is that glow from your corals that have green fluorescent proteins, or a few reds that have red fluorescent proteins, but a lot of oranges, yellows, pinks just don't show up because that light simply isn't present for them to reflect.
Comparing
any array containing only cool whites to an array based on Bridgelux BXRA or Rebel ES neutrals in the 4-5000k range will be absolutely no contest in color and depth while still retaining the same superior actinic response provided by royal blue LEDs.
As for their PAR value, the entire spectra of the white LED adds to the PAR value. PAR is next to useless as a metric because it simply the total quanity of light emitted - I can build an array that sends out 500 PAR at 24" yet will not grow coral, as the light will be solely composed of 530nm light, a spectra in which little to no photosynthetic activity occurs in corals.
A cool white LED does not emit as much photosynthetically active radiation (PAR) or photosynthetically
usable radiation (PUR) as a royal blue LED does (within the same family, of course - comparing an XT-E cool white at 1000ma to a Bridgelux BXCE royal at 700ma, for instance, isn't a valid comparison), simply because a white LED is a royal blue LED with phosphors applied to it - so you wouldn't be able to a 1600mW royal blue chip, apply a phosphor, and still have 1600mW of output in the royal blue spectra.
Taking into account that a cool white array typically uses a 1:1 ratio of cool white to royal blue, and a neutral white array typically uses a 1:2 ratio of neutral white to royal blue, an array based on neutral white will have the same PAR using
less total LEDs, or
more PAR if using the same amount.
Now, to address your issues with colored LEDs.
Note the
massive spikes in red. Despite numerous tests that have been performed (like the ones you linked to earlier), deep red does not bleach coral, at least not in the quantities we DIY'ers recommend.
If you blast a coral with too much light of any wavelength it will bleach, and in particular to a wavelength that the coral has no protection built up to.
Green is wholly unnecessary. All white LEDs contain far too much green as it is. What they are lacking is cyan, which is pretty essential in color rendition.
Now violet - this is the 'meat' of photosynthesis. You see that graph above, how it drops
sharply after 430nm? If you load up a tank with royal blue chips at 455nm or higher, are you really hitting chlorophyll a, the primary driver of photosynthesis in almost all corals, hard? Nope. It takes violet LEDs to do that. Chlorophyll C1 and C2 are different and can effectively use that 450ish-nm light, no sweat. However, chlorophyll c is present at 1/10 the numbers of chlorophyll a. (note that chlorophyll b, whose primary photosynthetic peak is at 450nm, is
not present in zooxanthellae)
Corals are subjected to immense amounts of violet light in the wild:
Feature Article: Light in the Reef Aquaria — Advanced Aquarist | Aquarist Magazine and Blog So if violet is the primary driver of photosynthetic activity, why is it unnecessary again?
Am I saying that royal blue and cool white LEDs cannot grow coral? Absolutely not. That has been proven time and time again. Is it optimal for both color and growth? No.
Back to the subject of neutral whites. Some 'light' reading:
LED Aesthetics: What do you really think of your color? - Lighting Forum - Nano-Reef.com Forums
The 'Evil Cluster' revisited - Lighting Forum - Nano-Reef.com Forums
A quote from the OP of that thread, blasterman:
More importantly, cool white rigs show off garish actinic colors better than neutral rigs, and will also show higher artificial PAR numbers. Since they are selling to a market demographic that's 90% under the age of 26 and likely will be in the hobby less than 21 months they want to maximize profit. I thought about building Bridgelux Array or Fortimo Linear based lights, and my rigs destroy halides having done the side by sides, but gave up when I saw all the BS out there.
The people in those threads are partially (if not wholly) the driving force behind the LED arrays we have now.
I think I hit everything I wanted to, but I'm sure I missed something.
) run about $50-$250 more but over a two to three year period pay for themselves in electrical savings and extra light. 
