I havent tried or bothered to learn any dubstep tunes. Havent really seen the point. But it do try and emulate different sounds set that i hear and from the different periods. Its alot more fun to come up with your things in this genre ive found. Earlier Dubstep is slower with a with not really any emphasis on this Dirty bass thing. Have a listen to Digital mystikz, Skream, Early Benga, Burial and a good few others. Then you get your newer stuff like flux pavilion, doctor P, Magnetic Man, and a load of others, just to name a few popular ones. Theres dub being mixed with jazz and everything now.
Id also get a behringer BSY=600. It has a not too shabby LFO in it and some other good sounds. Better then the boss and digitech IMO.