i'd be checking wheel bearings as well dude, seems like everything else has been covered. commodores had a similar rotor problem to this requiring constant disc machining due to excess runout and eventually revised rotors were released to eliminate the problem.
i'd check your wheel bearings, definately get the calipers reco'd to eliminate the possibility of them causing the problem. if fault continues look to replace your rotors.
i don't believe the slots would cause the problem.