I can just see four people driving around my house with these while im hosting.... leaving me the mess to clean up... I prefer emitters. though you can't crash into an emitter (yet), it looks better than a line of bricks that build up over time. If a host goes afk for 5 minutes his server might be full of trail brick by the time he gets back, resulting in rage quits.
Don't get rid of the brick trail version, it does have its uses and im sure its fun... but make a emitter variant to go with it... for movie perposes.