With the SMART system I don't think this game will be very custom map friendly
With custom maps you could end up with cracks between buildings that might wedge a small guy between them forcing him to sit in a crack and hope an ememy runs by to kill him so he can respawn.
Unless it's an outright map editor that uses a wide collection of set tile pieces that only fit certain ways and are already accepting of SMART (think old Tony Hawk games, Timesplitters, etc.) and not an actual map maker.
A mapping community could add interesting directions to how the game evolves since that would possibly allow for the smaller scale TDM type games (just for those maps) that some want, but also for some really long and indepth objective oriented set ups.