Nope. At 60 in a PvE environment you apply your assigned curse and then spam shadowbolt. That's it. You generally won't be allowed to apply any of your other DoT's due to the limited debuff slots.
Until you get a decent amount of spell/shadow damage gear it's actually not even worth casting shadowbolt. Your wand will usually be higher single target DPS.
Leveling two sets will definitely be slower than grinding dungeons as a 5man. Particularly as you get up into the 50's where you actually want to keep some of the gear you get because it's BiS for your preraid set. Far more efficient to farm this stuff as you level rather than grinding to 60, then going back to do Maraudon, BRD, etc.