Nice!
layer wound, for sure! With shielding between pri and sec! High input capacitance is not a problem, pri-sec capacitance is. You put the shield in the middle, ground it, you have pri-ground and sec-ground independent capacitances. You also want low leakage inductance, the more layers the better, but takes too much room and work with shielding. Usually 5 layers is good enough I guess.
As winding is easy for you you can use a layer of thin wire to do the shielding, may be easier than dealing with the ribbon copper, doing a complete shield and not shorting it, etc. I'm yet to build a good one, I never could get a decent core to do so, outputs no problem with the M6 I got.
JS