Although I already said it in post #2, once again thank you for this - with the help of your guide I've recently completed all of them. Just off the top of my head, some thoughts I had while completing them on how to potentially improve the guides:
Wastes: While this is definitely one of the most difficult ones, I'd *strongly* recommend the use of Furious Charge - Cold Rush (instead of Battle Rage). It makes this dungeon orders of magnitude easier, since Cold Rush stuns the big tremors! I've even toyed around with Leap (Call of Arreat for an additional pull, but also Death from Above for an additional CC) instead of War Cry. In the end, sticking to War Cry might've been better, but it worked for me. However, I definitely recommend everyone who gets frustrated to try Furious Charge. My route was to go to the left side first, just circle the two rows of swinging hatchets there, then go back to the big area at the bottom. Before I would go up through the left obstacle course I would make sure to have at least 4 of the 5 Rends completed - otherwise simply remake the game. The top area is a bit more difficult for kiting mobs around, especially if there are Tremors or elites left. However, if you have 4 (or even 5) of your Rends completed, you can entirely focus on killing everything on the right and top side - and with Furious Charge+WW it is virtually impossible to fail. Thanks to Furious Charge you can wear Focus and Restraint as well which means you have so much more damage, control, and speed...
Firebird's: I was really worried about this dungeon being one that requires a lot of gear tweaking - in particular, "nerfing your damage". Turns out that wasn't the case that much. I don't know why, but I had no issues setting large groups on fire (sometimes getting 2x the 20 mobs in one single pull) even with 1m+ sheet DPS. What I did was optimize for super maximum CDR (65% or so), such that I had Black Hole virtually up all the time. Also, reset all your paragon points on the first three tabs (except movement speed and CDR)! Restart the dungeon until you get a map on which you get the Meteor killing blow right at the entrance on one big pull - then you can focus on the first objective. After I had this done, what I would do is reassign my defensive paragon points (!) which would make it impossible for the mobs to kill me (400k life, 5m toughness seems to be the cutoff above which you virtually can't die in most circumstances). Then, whenever I saw a lot of mobs quickly cast Black Hole+Meteor+Disintegrate. I guess due to the delay of Meteor you can basically get them damaged from the first tick of Disintegrate before the Meteor hits if they're closely pulled together in your Black Hole. It worked quite well, even with high sheet DPS, and once you completed the first objective you can assign all paragon points to intelligence and the other offense stats, and at that point your damage should be high enough to blast everything away in no time. I'm sure I was just a bit lucky here, but I was surprised to find this dungeon much much easier than Delsere's - which took me probably the longest of all.
Unhallowed Essence: Only thing I changed was to move Evasive Fire off the left mouse button to button 4, which I felt was essential. It's so easy to accidentally kill Spiderlings with a left mouse button click. Also make sure to have no Thorns damage. Once you're sure to have absolutely no "passive damage", you can just Vault around on the left side of the map, like you said, to group up mobs and get at least 4-5 of the groups there - if not just restart, it's not worth it. After I took Evasive Fire off the mouse button and just forced myself to only attempt dungeons with a good spawn close to the entrance, it didn't take me too long (if you have a couple of 15-19 Spiderling groups at the entrance just leave right away).
Vyr's: I think the main difficulty that some people might have here is get used to the "fixed" teleport position on the Archon skill bar. What helps a lot is to put teleport on button 3 so that regardless whether you're in Archon or not, teleport will always be on the same key. Also, it might be a good idea to have Archon on button 1, because you want to be hammering it like crazy when you're in Archon form, but once Archon ends and you accidentally hit it 3-4 times all your Arcane Power is gone if you put one of the three buffs on there. Once you change those two skills on your skill bar, this should be a one-shot dungeon for most people; you got plenty of time, just scout every corner thoroughly before moving on and you're good.
Shadow's (Impale): I'm surprised to see this in top 4 of the easiest - I'd rank that one top 10, maybe top 5 of the hardest. But maybe I was just unlucky, or expecting it to be easier (did that as second to last), or maybe had some wrong gear. But I was failing that a lot due to running out of mobs and felt that are only 101 monsters in this rift... which of course is not true, but it was my feeling ;-) In the end I figured that having Impale on left click didn't work for me (too often accidentally double-hit a monster, breaking the chain, and then not having enough). I also didn't use Companion - the bats just killed some skeletons such that I didn't have enough left for the Impale chain. With those adjustments it still took a few tries... not sure why, but maybe if anyone else has a problem with that one those two pieces of advice might help.
Thank you for this thread! Set dungeon discussions come up every day on several sites, and it's nice to have one comprehensive and up-to-date resource to go to. Incredible amount of work you've put into all the builds, descriptions, and videos - amazing job. I'm sure this will be helpful for a lot of people this season :-)