I'm also curious; can I expect high CRI leds to solve the "grey light" problem outdoors with cool color temp leds?
If so, I have half a ton of lights that need upgrading...
This area is subjective, as some do not seem to report the "grey light" problem that others experience. Furthermore, those that do experience it also report varying degrees of improvement for the Cree neutral white bins such as the A and B series (5A is common) compared to a high CRI Seoul or Nichia high CRI LED.
I really like the high CRI Seoul, but it gives considerably less light for the power used and has a current limit of 800mA. The lower efficiency is due to the different phosphors used in this LED compared to most other LEDs. It also tends to produce beams with shifting tint from hotspot to corona. If you can live with no more than 100 lumens and the aforementioned characteristics, then it is a formidable replacement for incandescent lights of small size. IMO, it does a great job of eliminating the "grey light" problem.
Comparitavely, the Crees are quite a bit more efficient than the Seoul high CRI LEDs. They do not have high CRI like the Seoul or Nichia LEDs under discussion, but they do offer a noticable improvement over the cool white bins (even the warmest of them) when used in certain environments such as the outdoors. The drawback is less efficiency compared to the cool white bins, but the difference of about 15% is well worth the trade IMHO. The Cree will also produce more throw than either the high CRI Seoul or high CRI Nichia LEDs IMO. I still have not had enough experience with the Cree 5A LEDs to decide to what extent they address the "grey light" problem in terms of the confidence I have in my ability to accurately and easily perceive my surroundings such as when walking through woods. I can say that I appreciate the improved rendering of colors that would be present in the outdoors.
The Nichia high CRI LED uses an innovative phosphor blend that produces a light spectrum similar to that of sunlight, at least to a greater extent than any LED before. It's main limitations are the die configuration (6 dies over a fairly large area in LED terms), power handling ability (350mA), and low efficiency. It excels for use around the house or for close tasks, and just renders everything very 'naturally' compared to other LEDs.
The difference in these new LEDs is enough to make many converts. I will no longer buy a light using a cool white LED - with the exception of a Surefire Optimus. My lights now use Cree 5A (both XR-E and MC-E), Seoul 4000K CCT high CRI LEDs, or Nichia 083 high CRI LEDs. I also still enjoy various incandescent lights because these LEDs still cannot compete in the higher power classes. I suspect that will change with time, but for now I enjoy them for their efficiency, potentially excellent dependability (depending on component and build quality), ability to dim without yellowing, and no burned out bulbs.