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This is the problem with modpacks, every player is different.
With the new 1.7 I'd changes it will be muck easier to make your own pack to suit your needs and wishes, and editing existing packs also will be easier.
For more info, go into the cofh config files, (there's several of them, I think it's the one called cofh world) and edit away. You can adjust the rarity and the size of the veins