- horizontal directivity seems a bit more linear/consistent than IN-5.
Just to play devil's advocate here a bit, I actually think the IN-5's directivity is better or at least not worse. The LP-6 has some clear issues in the crossover region, which are a bit hard to see in the contour maps, but if you look at the Sound Power DI the broad spikes and dips in the 900hz-2000hz region are clear. The IN-5 has some issues too but they're at 5khz+ where they are less impactful IMO.
A significant portion of the LP-6v2's flatness advantage is also below 300hz. But I consider this region unimportant because it's so heavily impacted by the room and you will(should) be EQing it to correct those issues anyways, and the dispersion is omni so that's not an issue. It's similar to how the inherent FR of a subwoofer is relatively unimportant if you're EQing it, there's no directivity to worry about and room issues dwarf any variations in the speaker.
has better preference score (5.9 vs 5.4 for IN-5)
In addition, 0.5 is less than the 0.8 required for 1 std dev(~66%) confidence that one speaker will be preferred, in fact the chance here would be about 45%. This is such low confidence that a blind test could easily go either way, especially when you consider the score does not consider different frequency regions more important than others, so it undervalues flatness in the most audible regions.
That said, this comparison is pretty educational about why coaxials are rare. Even with a larger budget and a highly competent designer, you can see how challenging it is for a company to beat their own traditional design.
But I do think the IN-5 could be preferred in many cases, and personally(if budget allows) I would prefer it in a nearfield console/desktop setup, where I think vertical dispersion is most important, due to the significant height angle variation depending on how you sit, and also more even reflections off the desktop surface.
There is no question that the LP-6v2 is the value king. However all Kali's speakers are very good value compared to our gold standards like Genelec/Neumann or even Kef.