The DC in its current form is useless. Give it a healing capacity that is almost that of alien buildings, because otherwise the human team is always dimished by one person, who has to keep repairing the base, tilting the balance much to the aliens' favour. Mind that in stage 2 the aliens have advanced dragoons which can spit barbs and advanced marauders with their field zap attack, in my opinion, this requires a much harder balancing than is done now. I experienced several times where, once aliens were S2, the human team could not leave the base any longer because they have been kept busy by aliens zapping and barbing their base, even if the humans were S2 themselves, because the DC is worth nothing in the current form.
Give the DC a healing capacity of almost that of alien buildings, do not make them stackable, in higher (not to say unlimited) bp-servers this makes human bases almost indestructible.