this topic has been beat to death on here but the answers basicaly lead to a few conclusions.
Street charger only trickle charges and is not a replacement for a deep charge.
street charger only works well on cars that are driven. if you dont drive much it wont charge.
when people use it in conjunction with an at home charger they have good results
ive got the 48v streetcharger in my daily for 4 years now and i dont have any problems and you should not either as long as you drive the car if you dont drive it or just on weekends it will be a waste of money. i still put my batts on the home charger once a month