I have been in the MK at official park closing on non e-nights when the crowds were very light during the last couple of hours. This was not the case on e-nights that I have been there; it seems that there were people there for normal park touring and there were additional people there for e-night. From what I've seen, MK can be more crowded on e-nights prior to official park closing. I've planned our next visit so that we will be in MK on a non e-night and will not be there during the evening of an e-night that we will not be participating in (we plan to do one e-night during our stay, but there will be 2 opportunities).
I'm not sure how well my strategy will work because each night we are there, the MK is scheduled to close at a different hour AND the non e-nights have Spectromagic and Fantasy in the Sky scheduled. It could turn out that those nights are more crowded in the evening than the evening hours on e-night prior to the start of e-night. Special events, days of the week, and closing times of other parks may have a bigger effect on the evening crowd at MK than the e-night participants do.
(Most of my sentences drag on because I'm trying to make it clear that I assume the OP is addressing the crowd size in MK during the evening hours prior to official park closing and the start of e-night.)
The ee mornings are now called the
Extra Magic Hour and are scheduled as follows:
Sunday - Magic Kingdom
Monday - Disney's Animal Kingdom
Tuesday - Disney-MGM Studios
Wednesday - Epcot®
Thursday - Magic Kingdom
Friday - Disney's Animal Kingdom
Saturday - Disney-MGM Studios