Originally posted by kenyee By PF, are you meaning Purple Fringing?
This is really a DSLR urban legend. Well-spilling sensors are things of a long-gone past, and any purple fringing is only caused by the lens (and accordingly to some sources, possibly the sensor's microlens array, but I don't think so).
One easy test to convince yourself is to use an higher ISO : if the PF stays, then it has nothing to do with electrical spill from one photosite to the surrounding ones, as you don' fill them anymore.
You can also try to defocus the lens a little bit, you'll then see the PF go away!
Or maybe you simply implied that the weaker AA filter had a detrimental effect on optical PF, in which case I'm with you!