haha, i think i feel what you are saying op. there probably won't be much yield difference if you wait, they might swell up a bit but i would cut for the high your looking for because the yield difference will be negligible
ec reads your electrical conductivity, aka how much nutrients, ro water will base between 0-50 ppm tap is usually 150-250...most of the numbers in the tap is cal/mag
It doesnt matter if one is actually said gender does it? its how they identify and i agree if possible it would be nice to add the option to change it :)
you going to use that epsom foliar? id reccomend. but if you switched to ro i would also recommend picking up some cal/mag to bring your ppm's back up, take this with a grain of salt as im no hydro grower.
looks like zinc def to me.. http://www.growweedeasy.com/zinc-deficiency-cannabis, also i've had something similar to this happen when there was to much temp variation between night and day