Haha, okay so obviously the K series are very different from the standard Filco/Cherry/SP keys!
Since I put them on the function row, and I barely use that row, I haven't really felt any difference. I think that the J series keys feel slightly less flat in comparison to the standard Filco keys, but that might just be the texture.
I've moved the K series to the number row now, but again, I don't really use that a whole lot... If I had enough to cover the alpha keys it'd be great, but I didn't order that many. The surface of the key is much large and you keep your finger much higher than the J series keys... I can take some photographs for you to compare the heights. I'm not so good at describing things... Also, Devlin/QWERKeys refer to the rows the same way it seems. Row 3 is home row.
I am trying to notice the difference in switch feel... but it's difficult to judge. I only have MX Black for now. Still waiting on the Phantom GB to be shipped for me to receive a few hundred switches to try different setups with.