I do 3200-3400 single target DPS on target dummies in pretty good gear. Whilest I can reach 4500's raidbuffed. (No castsequences).

Target dummies often do not reflect your 'accurate' dps (nothing does as it relies on many many different things), however they are a great means to find the DPS method/rotation that suits you best. If you want to get the most out of it, don't castrandom or sequence though and do it manually. If you run a multiclass set up however it might be hard to fit in proper. Maybe find a middle-road. (ie. splitting up Flame shock from your castrandom.)