Having used the K540i and the ZCO 527 in rimfire matches, I can say I much prefer the 540. Below are some reasons why:
Field of view, although maybe not a huge difference between the two, there is a difference.
Love the SkMR4+ reticle. Some have said it looks too fine, but too me it’s perfect. Also, I pick up the holds much easier than with the MPCT1X.
Top turret parallax adjustment. The parallax also seems much less finicky on the 540.
Glass between the two is subjective. It’s very difficult for me to see any difference. Both are fantastic.
It’s also way easier (for me) to jump behind the 540. Not sure exactly why.