Update:
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Dungeon runs, feedback:
SFK at level 26. Ran it several times since I wasn't entirely pleased with my first go, also allowed to gather the shield, ring and Meteor Shard.
BFD at level 27. One time since I got all that I needed and felt satifisfied with my results.
Both times had DPS my own level. For the previous entry-level dungeons I had tried to keep them a couple of levels below me just to be able to cope with their dmg while I practised. This time I decided to go for it properly. Single target is never an issue, which means boss fights rarely give me any trouble. BFD trash is pretty easy to handle, even if the disarm on satyrs hurts your rockbiter weapon threat (since you can still lightning shield + shock them, it doesnt punish you as severely as it does a warrior). The turtle pull at the altar just before Aku'mai seems like the only real potential problem I found, since 4 targets, all of which have a chance to knockback can be a bit of a problem. 1 or 2 CC renders it easy nonetheless.
SFK though: The magic immune shield worgen occasionally cast makes them immune to your Earth Shock as well as your Lightning Shield. Shocking them while casting it doesn't interrupt. My advice is to cast the spell early on, and then rely on rockbiter. Most of the dungeon from beginning till Odo is largely uneventful, only Odo's fight (having 2 bat adds pulled with him) requires you to do proper multitarget control. The packs leading to Fenrus, and the fight with Nandos though, will be your real test. The pull in the first tower room that has 2 horrors and 2 worgen requires you to stoneclaw, and if tauren, warstomp. You need to not only control the 4 targets but also be able to coordinate your team to burst the horrors before delusions get out of hand and kill your healer. Nandos' fight is uneventful at first, but by summoning ads when he's at low health, one of which is a Lupine Horror, the team must either CC the new wolves, or switch DPS to the horror. Hard to pull off since pug DPS generally don't do on-the-fly CC, and getting them to stop bursting the boss and go for the snowball add isn't that easy.
Arugal is pretty easy as a shaman tank though, this is your boon. Comparing it to the times I did it with a warrior or paladin I can vouch for this. Earth Shock's cooldown is short enough to be synchronised with his own spellcasting. Time it correctly and he'll rarely be able to get any spell out, by the time we killed him, he only managed to get one single teleport out.
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Spell use and stats:
What I've come to find is that maximum uptime of Lightning Shield, is very useful. Case in point: 3 mob pack, rogue in team will unleash every single thing he's got on the main target, giving little space for you to slack. You still have to account for the other 2 targets in order to stay above heal threat, so hitting them/shocking them at least once is necessary. Having dmg being done whenever you're being hit, builds some threat on targets you're not currently hitting. If a secondary target gets the lighting proc, you can afford to not him for a few more seconds. If the primary gets a proc, you can afford to hit another guy. In all regards, the absence of cleave-like moves (swipe, or the easy mode consecration) is one of the main concerns you need to be aware of and counter, and thorn dmg is a good workaround I've come to find.
In order for you to be able to keep lightning shield up for a majority of the time, you need to downrank midfight, and use max rank only when doing the first pull. On top of this, adding some Intellect to my stat set-up seems to yield positive results, not only for this purpose but to squeeze in an extra Earth Shock (I use 2 ranks of this as well depending on how dire I feel threat generation needs to be). Always pull yourself, if a regular trash mob, save mana and use lightning bolt rank 1. If a mob that stuns/incapacitates and can screw your threat generation, max rank lightning bolt + max rank Earth Shock, on top of the first lightning shield proc as well as 1 hit on rockbiter will surely be enough for you to recover.
My stat priority as it stands then is stamina (obvious tank choice, maxxing it compensates for lower comparative armor from leather), followed by strength and agility in similar doses, and intellect complement. This is for lowbie gear. I will re-assess this when nature/spell dmg, is an option, along with more specialized stats.
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A look at weapon speed:
Regarding weapon speed: I currently have both Meteor Shard from Arugal, 1.80, and I procured Vendetta (1.30 + 6 agi) from the AH. Tested both with KTM + using each of them in a different dungeon run.
I had done the previous math work on top of Aethelwulf's insight, and decided to theorize on it: A faster speed does represent a higher likelihood of Flurry uptime/minute. On top of this, speed reduces the punishment you get from a dodge/parry/miss, and more importantly: Target swapping requiring 110% threat on melee and 130% threat on ranged, means that you should always strive to keep a quicker, even if lower, threat generation, over a delayed, even if larger, threat generation, since mathematically speaking, it is always less costly to keep a target on you even if barely, than try to regain a lost target (lost targets also represent no thorn dmg being done, and in the case of dumb DPSers, threat dmg being done on their part if they didn't toggle off these options).
However, lower speeds do get one thing in their favour via Flurry. Since the attack speed boost is % based, a 0.3 reduction to swing time means that the absolute reduction will always be larger on higher values (slower weapons). Case in point, Meteor Shard having with the increased speed (I was 3/5 Flurry), puts it at 1.5 speed (0.36 reduction, always rounded downwards), while Vendetta's reduction will put it at 1.1 speed (0.26 reduction, rounded downwards to 0.2). This means that when Flurry does proc, slower weapons end up outclassing faster weapons in terms of threat generation. By trying this out in a dungeon, it worked precisely like this, every crit followed by Flurry on Meteor Shard was a really nice spike in threat, compared to Vendetta. After all, 1.8 threat was being applied on a 1.5 speed, resulting in better numbers than 1.3 threat, applied on 1.1 speed.
Regardless, my impression is that the advantage Flurry spikes give to slower weapons, aren't enough to match the advantages of faster weapons. To begin with, the spike in Flurry requires... well, a crit to begin with, slightly harder to get going with a slower weapon. A dodge/parry really hurts you much more, specially if you get a rough patch where Earth Shock was resisted as well. And finally, threat being the multiplicative thing it is, it will generally benefit you to put as much early threat as you can (by faster speed) even in lower absolute amounts, compared to higher amounts that require a longer swing time: If you put 216 threat in 2.5 seconds (2 swings,each for 108), your melee DPS will need to do 237 threat to pull away from you. If you put in 140 threat in 2.5 seconds (your second swing will come by 3.0 or later), your melee can pull away from you by just doing 154 threat, which isn't unfeasible for a bursty rogue that opens, auto attacks and follows with his first special in less than 2.5 seconds.