Wow, 4000K has always been my favorite tint going back to XM-L2's, maybe XM-L's, not sure. But that one seems to have no hint of yellow at all.
I've had various tints in mods, intentionally, and every time I'd compare, the "5X" would be my favorite. 5B1's or 5D1/2/3's are real nice. Dropping into the warm ranges wasn't my thing.
The 5D2 IOS sold way back was highly regarded: https://budgetlightforum.com/t/-/22306