One must be careful when talking about things like heat. I would assume orbital "Chaff," or reflective particles, that scatter light of all wavelengths (including infrared) and prevent it from reaching the planet. the particles we're discussing are orbital and above the bulk of the atmosphere, so absorbed radiant heat is essentially irrelavent at the planet's surface.
Either way: anti greenhouse gas is nitrogen + magic technology. I support magic.
Future terraforming redesign has been mentioned by steve, where things like magnetic fields and hydrospheres are important. I would love to harvest cometary bodies, or iceworlds, of water to establish hydrospheres elsewhere. Water management is a HUGELY important part of space colonization. As it stands now, we can create a wet atmosphere, but I don't think it will ever rain out as a hydrosphere. I'm sure any development in these areas will complicate the use of anti-greenhouse gasses slightly, and perhaps effective limits will be instituted as a result of changes to the design. (its crazy i can do a 3000 degree C ball of useless, airless rock, with no hydrosphere or magnetic field, to a viable 0 cost planet in just a few years with AGH gas.)
As an additional side note, lack of a magnetic field should cause atmosphere to bleed off as a function of proximity to star and luminescence of said star. So that 3000 degree ball of airless rock would quickly become airless again without hundreds of terraformers operating at full capacity.