This.As much as I love Biome's O Plenty, it's one of the mods I leave for Mystcraft. IE, I turn it on, and then use default generation and let Mystcraft build BoP worlds. That way I get all the benefits without the hazards. I definitely want to try out Highlands, if only for Flying Mountains.
I learned it in a hard way. My current world has no Magical Forest thus no Greatwood (Found Silver wood in Ominous Woods), and border of biomes always a sharp cut aligned with chunk borders.
TLDR, use default world type and with added biomes to default world gen option on.
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