The real question here is "What is your definition of "serviceable" DPS? And how is this the same/different from any other class or archetype? I think I do pretty serviceable DPS as an Enchanter. But that is probably because I solo and have no real comparisons to other classes/archetypes. What I have noticed is that my DPS gets better and better depending on a number of things: ALWAYS be leveling up your skills. As an Enchanter I swap my weapons frequently to make sure that my staves and daggers are maxed. You never know when you're going to get a special version of what you like or don't like. It is better to have your skill maxed than to wait for an item and then having to spend a long time leveling up because we ignored it. Next, always go for that weapon upgrade. It DOES matter from one level to another. FOOD is another factor. As an enchanter I don't have much use for something that gives me +2 AGI. At least not when I can carry food that gives me +1 Int (+damage and + mana amount), food that gives +1 Wis (also enhances my spells but also gives a higher rate of gaining skill ups), or even food that gives +10 run speed. Your food matters. Never be afraid to ask in chat for food for your class. Tanks would love to have food that gives +100 block and +5 parry. Another thing to consider is your own abilities - learn them use them and most importantly, when given the option - throw some Master points into them. Lastly, consider your role in the current encounter. Are you a DPS machine or is your job to take a pounding while others DPS? Having a second tank can be fine if you are expecting adds. Your DPS may not be as high as a rogue or a wizard, but if you have to hold a mob for a few seconds, your "serviceable" DPS is more along the lines of taking the heat until help can be had. Even if your DPS is lower than the rogues, it is still "serviceable" as an off-tank.
On my paladin my DPS was pretty low until I got a nice 2 hander with about 13-15 damage. Then, your damage will ramp up again when you get the Oath of Might ability which practically doubles your dps at low levels.
If we had to pick a tank to do dps in a higher level group, which one would you pick over another? I want to test out the tanks, but playing a character with a singular role means you are pigeonholed in a group. Since each group needs one tank for the most part a pure tank will spend more time lfg than in group, yes?
Playing a warrior, and doing pretty well in the DPS role, when I'm not tanking. (still adding a lot of group DPS when I am tanking)
The warrior brings some utility that multiplies the DPS of the group as a whole. Specifically, a shout that increases everyone's physical DPS by 20% and an armor sundering ability that reduces the monster's armor value by 5% with every stack (up to 25%). If you have a heavy physical DPS group, I'd say that a warrior is an MVP. Increasing the whole party's DPS output significantly.
That said, I wouldn't have 2 warriors in a group, as these abilities do not compound with a second's.
If I had to guess, a melee centric grind group with a warrior, dire lord, rogue, monk, and 2 supports would do quite well. I'd imagine optimal supports would be shaman and bard. This is purely my imaginings. Still not nearly enough data, and no data for the bard. I'd imagine the bard will have an ability set that helps multiply the group melee damage with bolstering songs.