Melee DPS Group - Bard vs. No Bard
 

Who does more DPS:

Group 1: Shaman (0 DPS just healing), Rogue, Rogue, Rogue, Rogue, Rogue
Group 2: Shaman (0 DPS just healing), Bard, Rogue, Rogue, Rogue, Rogue

Assume all group members are fully raid buffed and this is a fight where resists don't matter.

Raid buffed and geared?

Hands down, a melee group with a bard does more damage. Atk song and, ideally, epic proc make a huge difference.
Erjavavsjvs, less so, but it's something.

Rogue x 4 (or x 1 ranger)
Healer
Epic Bard

Is the group I form for pretty much anything besides heavy AEs. I drop a DPS for a second healer in that case.
Shamans are awful healers for a rogue group BTW, because they think their mana efficiency is important for some reason and torpor you.
Clerics are busy usually. So druids are my go to.

If the bard has epic + siren song, I would take the bard group.

Any other setup, that shaman is going to be hurting for mana.

Bard group will kill faster in this situation because:

-bard can lull pull
-bard can EASILY hold aggro allowing all rogs to backstab
-bard snap aggro means instant sham slow without ping pong
-bard regen songs (mana and hp) really cut down on or eliminate down time

Individual mobs might die slower but with the bard you will kill a lot more over time.

I mean are we talking about raiding here or exp efficiency? Just raw damage, you want your 4 or (5 even) best rogues with a bard because it's ~6%+ extra damage per rogue. You don't need healers in non-AE situations if you pay attention.

All things being equal. On a fight like Vindi with a 30 man force.

The individual rogues in the bard group will have higher dps.

The group with 5 rogues will do more overall damage than the group with 4 rogues and a bard.

Yeah, since the bard bonus only works out to a quarter rogue extra damage. So 5 should win. Doesn't seem to work out like that because things aren't equal very often.

DPS per single encounter: Probably the 5 rogues (by a small margin)
DPS per time: The bard group. By a HUGE margin.

Obviously, five rogues will do more damage than four rogues. The four rogues will have higher DPS per rogue, but they're not going to overcome an entire additional rogue. EverQuest is pretty much a numbers game.

The question is how valuable you value the decreased downtime due to hp and mana regen, damage shields, and ability to pull and crowd control more easily.