Yuki Nagato will do these expository encyclopediac bursts but Mai simply compresses more nuance of emotion into a grunt or a short phrase than most people do chattering all day. Characters like Sakaki (AzuDa) are homages to her type (although Motoko (LH)) is in the family here, she's far more talkative).
I like all the archetypes exemplified by the characters in Kanon , but Mai is just especially endearing (particularly when I think of this solemn girl in her special headdress
) Some echoes of the headdress Setsuna (Negima) wears at the festival I suppose