The Spirit Realm

From numerous Vish attempts already, best getting him to 17% before the !@#$ hits the fan, Vish, imo, is not that difficult up until 25%, if your entire raid is focused and does what they are required to do, then it's not that difficult. However the script itself is on a whole new level compared with Rikk/Kess/YarLir, also we have been farming anguish for a while minus OMM of course. I would recommend you do Anguish first as there are plenty of upgrades and the 2.0's would help immensely. The difficulty does come from the script for the most part.

Honestly the MPG trials and then Anguish itself are basically all a fair bit easier than Vish, and while Vish's loot is amazing you get a lot more bang for your buck clearing trials and Anguish content, thus gearing the raid as a whole up more, thus doing more, more quickly, to make Vishimtar easier

Is vish possible with out anguish gear? yeah definitely. There's nothing in the fight that would truely require anguish gear. Vish him self doesn't hit all that hard to require a better main tank. Mana issues can be worked around by killing more mana clouds etc but the biggest threat with vish is someone dying and spawning an add because that just starts killing more people and spawning more adds. The lesser geared people are the greater the odds that will happen. Of corse the more dps you have to make the fight go faster the better and anguish with epic 2.0s do well for that.

I don't think Vish loses one percent of life per cure, it only allows you to dps him down one more percent per cure, so dps is still a factor at 25%

I disagree with people saying to do MPG & CoA for loot volume instead of Vishimtar. The particular problem I think is that killing Vishimtar isn't about loot volume. Sure, the other stuff is good, but kililng Vishimtar is all about Eye of Vishimtar. That drop is available nowhere else, and produces uniquely powerful items for many (not quite all anymore, rangers are an exception) classes, with great stats. Pretty much every member of your raid force will want to loot the Eye before you move on from him. Waiting four months to start on him, if you can start on him, means farming him for another four months somewhere down the line, when perhaps you'd rather be working on your strats for Snowtail or Daosheen.