[spacebird]

as cober said, they gain one level at a time. the second tier of any stat will still only give you a +1 in said stat in addition to the +1 you already bought.

as far as i can see, there is no difference in how each borg operates, whether it be more expensive or less expensive. you are paying for the less humanity lost. the higher cost/less humanity borgs are the way to go unless you want to be a weak ass n00b borg like superdave [24993]