As a Engineer i am a acid dps, 777,666 in runes, pat 5 and victory cross, instead of using swiftness i use crit chance, the damage i do is pretty good, much better than swiftness, best thing i would suggest is to just mix and match stats to get what you want.
Now for single target vs AoE depending on who you run with then dps will vary but most people you can out dps and sometimes on the boss you can do alot better than some, so i say its bs that engineer is lowest dps, it is about the middle.
For my stats i do Crit Chance around 200+ mark, det as high as i can get it and Natural Damage at 150 average, defensive stats Survivability, Concentration, Bloodlust
my dmg range is 1m - 7m dps and sometimes when i crit can hit 11m add the order bonus of 30% dmg i can crit 15m dmg at times.