Can't say it's "real" but I think the K series sights have a better dot. No idea why but I noticed it when I got the first one for the Shield Plus. Got another one for the Shield Plus slide that ended up on the Shield frame. Got another one for the Equalizer. Got another one for the second Shield Plus.
Consistently clearer, round appearing, etc. over the full sized Holosons that I had an older M&P 1.0 sub compact .40 slide milled for a K series and it worked out great. If, in the next few months, I go ahead with another project on the M&P platform that compact will also get the slide milled for a K series. For one reason or another they just look better to me.
I also believe the larger dots (4MOA or 6 MOA) are clearer than the smaller (2 MOA) dots. I wonder if that's a brightness issue. I can see the bigger dots at a lower illumination setting.