Shouldn't need to even include maps in downloads.txt.
Maps will automatically download if the fastdl has it when a player joins if he/she doesn't already have that map.
Downloads.txt is primarily meant for one-off sounds, models, etc not already part of a addon or pack.
Sure, you could USE it for maps, but I'd hate to join a server that forced me to download 10 maps when I first joined, to never return after one map.