I got some info from Michael. This is what is said about the difference:
"Both the 219 and 319 use the same capsule and electronic circuit. The MK-319 Floating Dome or Flat Top is a better choice for OH or other applications where you want to capture smooth off-axis sound. For close up vocals there is not much difference, though the MK-219 has a tiny bit (1-2dB) more lower midrange presence than the MK-319 due to the different headbasket and grille."
About the flat-top dome-top thing, he explaines that these mods are made to reduce standing waves inside the basket, by removing the upright bars inside.
This is to decrease off-axis coloration.
The bars also act as resonators, much like tuningforks he explaines, so by removing them, the clarity is increased.
The difference between flat-top and floating dome are largely aestatical he concludes.
That answered my questions, if u have some more, mail/pm Michael I would suggest.
I went with it and bought the MK-219 with PEO, and I hope I will be very happy
Pzz & happy newyear to all!