I did some more research on chloramines, and found this:
http://www.wqa.org/pdf/TechBulletins/TB-Chloramine.pdf
Which says: A) chloramine molecules are small, so it's "difficult" for carbon filters or RO filters to remove Chloramines.
B) The most effective method of chloramine removal is activated charcoal, which does not adsorb it, but rather acts as a catalyst to break it down. Some ammonia is created, but mostly it does this: 2NH2Cl + CO*= N2 + 2Cl(-) + 2H(+) + H2O + C*
C) A bed contact time of 10 minutes or greater is required for complete catalysis of chloramines.
Probably we're not aiming for 100% reduction in chloramines, so the bed contact time could be shortened, but any flow-through filter for home use doesn't have anywhere near 10 minutes of bed contact time. If you have a .5 GPM filter, and your filter volume is about a quart that implies a bed contact time of no more than 8-10 seconds.
What am I missing? Is the quoted 10 minutes incorrect?