So I ordered a 20mm quad MCPCB and 4 of the XP-G3 R2 3000K 90+ CRI leds, and paid the small fee to have them reflow soldered by Mountain Electronics before shipping, then swapped them into my Cool white HI D4 on the kitchen table...
Now I love the light. I hadn't been able to enjoy the low levels of the cool white at all, but at 3000K the floody lows are fantastic. True to the prediction of the Kruithof curve, the high levels are yellow and glaring, and less "pleasing" than the cool white's high levels had been.
It also gets hot very quickly on high.
With that all said, it's just about what I'd hoped for and much more suitable for the majority of what i need a light like this for, say 10mA to 2A with scrolling brightness control.
Next to get another one in the 5000K Nichia high CRI flavor to compare brightness and rate of heating.