crashlog : http://pastebin.com/jg8KyDrw
Ok so first of all in the config I've set Wasps, Phantoms and other nether mobs to ID=0 ( that's a way I found on reddit that disables BOP nether mobs). I've also disabled all nether biomes from BOP(Undergarden, etc..).
The crash happens (I believe) when the game tries to spawn these mobs with ID=0 because the first line of the crash is
[15:52:57] [Client thread/WARN]: Skipping Entity with id 0
and after that the game crashes. I should note that I tried flying around in the nether in peaceful - no crash for half an hour, go to normal - crash after 5 mins.
BOP: latest for 1.7.10 - 2.1.0.1067