Spent way too much time in pugs doing O2S who couldnt beat the enrage timer.
I didnt know who was holding who back, and even questioned if it was me. When I got a raid group, they told me I was the highest DPS of the group, and above what was needed from me. So I can say having a means to see your DPS helps a ton.
BUT
Having mid battle parsers does create problems.
I'll give examples real quick, and then talk about what I think is a way to implement parsers.
This obviously doesnt apply to everyone, but WoW is the best example of how people get, when something becomes normal, and people start trying to min/max.
Some jobs dont do as much dmg on their own, but contribute to raid dmg.
If their DPS is low, and people expect "X"dps per person, they can and have kicked people who dont deserve it.
Another example in WoW, but not here, are people who do more dmg at the end of a fight, and it is so high, it makes up for the lack of dmg throughout 75% of the fight. (atm this is shadow priest in WoW)
When they never make it to the end, they look and see a DPS who's doing 20% less DPS than the rest, and they get kicked.
Lastly, is AoE vs Single Target. Less important in savage, but in basic farming roulette dungeons, the jobs that do less AoE dmg will also be kicked, because those who do AoE are going to show a higher amount of dps.
(Ive also ran into people who kicked people out based on what % of the enemies HP they dealt in dmg, rather than DPS. For example, this Warrior did 10k dps. and the leader of the group said everyone must do at least 7k dps. The warrior was kicked, because the other DPS did so much more DPS, that his was lower than their by comparison. The leader looked at how much of their dmg was X% of the bosses total hp. This one is just weird, but i saw it alot in cataclysm, and not as much now.)
The most frustrating thing Ive seen a group do, is kick people who werent pulling.
Essentially ive seen SOOOOO many Hunters, even today, who's DPS is terrible.
So they run ahead of the group, being the 1st to fight, and getting off attacks before melee get to the mobs.
Some people leave the parser going between pulls, therefor the person who gets to mobs 1st has higher DPS. Even if their DPS is terrible, if you only count "in combat" DPS.
This is the MOST annoying one for me. This is the 1 thing that can never be avoided, if you openly allow parsers mid combat. People wont learn their rotations, but instead learn to just run to mobs before the rest of the group. (You can tell they do this because their DPS numbers are different from the rest of the groups, who actually dont keep track of the down time between mobs.)
I also think thats where they stopped looking at DPS, and at total % of dmg done in a dungeon back in cataclysm.
Now, as to how to add parsers.
Personally i absolutely HATE how the game locks you out of content you havent cleared yet, even if you're able to clear it, because clear groups arent capable of doing the fight yet.
Instead, it should be a check mark based on ur ability to handle the test dummy. "Did they beat the dummy and survive?" (survive for healers/tanks)
When they beat it, it should keep track of your recorded DPS, and TELL YOU what it was, so you actually know how much room you have for improvement.
And when people make party finder groups, it should only look to see if you can beat the dummy, and then the leader should be able to look up the record of what your dps was when clearing it. (only showing the DPS of the hardest test dummy, not for each test dummy.)
This both helps players know what thier DPS is, lets a PT leader see what they could do, if given time to learn a fight, lets a PT leader know if they got carried or not last group, if everyone's DPS together will be enough to clear. (in case someone is just shy by a few points for some reason)
Also, the problems i mentioned above cant be caused by this implementation. (It may cause new issues, and of course would be re-evaluated then.)