I'm with Gyppo. Either is fine, but "them" works better. Sometimes, while acknowledging their skill, it's necessary to show the grammarians a yellow card. Perfection is sometimes uncomfortably close to pedantry.
If someone challenges it, hit back with Churchill. Someone typing out a speech for him amended a sentence which he'd ended (shock, horror) with a preposition. He struck out the correction and wrote in the margin: "This is something up with which I will not put!"
ps: These are not dumb questions. They concern the building-blocks of our language and our literature. We should all be trying to get the components right.