I think the mainstreaming of ECVs in the busy MK and Epcot lines works ok - I've personally not had a problem. However I did notice in our trip a couple of weeks ago that one evening leaving Epcot after fireworks the lines to get on the bus at both the Pop and AoA stops (next to each other) were massively long - and no busses came for probably 15 mins making them just the longest lines I've ever seen for a bus. Finally some transportation people came and then busses started coming one after another. By the time I got to the pull off spot there was maybe 4 chairs in front of me - I had to wait for the 3rd bus. However by the time I got ready to board there was a line of
ECV's behind me about 10 deep - it was nuts! Those people were going to have to wait a really long time to board as an ECV user. I guess they wouldn't have gotten on any faster since each bus can only take 2 and every bus loaded 2 (no busses were leaving without having 2 ECV's loaded).
One evening after fireworks leaving the MK I had an ECV user literally speed around me and my friend (going full speed) and cut in front of us at the very last second before I got to the end of the line which was so long it had ended up outside the metal gated spot. I mean like we were a few feet from the end of the line. To top it off her friend in an ECV was somewhere behind her and actually rammed into my ECV trying to go through ahead of me in order to catch up to her. I was dumbfounded at her especially - never had someone hit me on purpose! Eventually they sped off together (full speed!!) to another line because I guess they thought they'd gotten in the wrong que but they later came back and ended up behind me in the line - deservedly so. They were so dumb it was kinda funny but it really makes you wonder what goes through people's heads when they do stuff like this....on purpose.
I generally won't stay for fireworks anymore - lol! It's just a nuthouse getting back.