Upon updating to the latest version of the modpack (1.2.0). I discovered that my enderman farm's efficiency drastically decreased. I didnt think of the pack version being a variable, so i ran quite a few tests and happened to accidentally downgrade a different instance of the pack. I found that the spawn rates are essentially 1/4 of what they are in vanilla and previous versions of the pack. This should probably be put into the bugs thread, but i do not have permission to post in there. Here is a video of the difference in spawns.