My opinion is true urban assualt and street riding is best done on a hardtail, where you can keep the weight down. Technical stuff will be easier, and it will teach you how to be a smoother rider. MANY people ride hardtails for urban (i'd say the majority) there are reasons. Also less things to worry about, 1 brake, 6 gears, 2 wheels, 1 shock, and a frame.
Just my 2 cents
Peace