What is peoples opinion on the 4p t13 set vs 4p t12? I recently swapped to t13 and I feel unsatisfied by it. Currently i am concidering going back to t12. Any math done as to how much it affects us in either a AOE or Singel target fight?

Just comparing the two sets, 4pc T12 > 4pc T13, without a doubt. 4pc T13 is still a bit lackluster, and the only reason we upgrade to a full set of T13 is because of the stats to beat out 4pc T12.

Since the 4.3.2 patch, I believe it's now ok to upgrade from 4pc T12H to 4pc T13, as the latter is a little better. You'll notice a bigger difference once you start getting into 4pc T13H.

Even though the stats are better, it kinda feels grose to use it. Might be because I have been using the t12 for so long that I have gotten use to go between eclipses like a blast. I am thinking about going back into t12 heroic instead. I dont have much hope for clearing DS heroic anyhow(kinda slow progressing guild).

For how long would it be acceptable(dps vise) to stil be using t12?

It'd probably be acceptable if you had 4 pieces of T12H, and then your off-piece being the T13 pants. If you can't manage that, you would be significantly hampering your DPS.

Looking at your armory, I'd say stick with your T13. Only thing you could improve would be getting the boomkin T13 shoulders + resto T13 chest (better optimisation).

It's pretty dangerous and borderline misleading to talk so much about whether we should, as a blanket proclamation, advise 4pc T12 over 4pc T13. For many of these fights, you want to hold your spot on the eclipse bar or make the most out of your eclipse, which renders the T12 bonus borderline useless.

Take H-Blackhorn and H-Spine as examples. On the former, you want to hold Solar for all of P1, and your dot damage is critical. On the latter, you want to hold just-before-solar when you're 30s (or less) away from the tendon burn, and your damage in that following eclipse is what matters the most. In both cases, 4pc T12 is vastly inferior to 4pc T13, despite Patchwerk sim numbers.

In fact, I can only really think of 2 heroic fights where the T12 setbonus could approach that Patchwerk sim: the easiest fight in the instance (Morchok) and the one Patchwerk-like fight of the tier (Ultra) - which also happens to be the second-easiest. Advising players to hold that set bonus when the only two fights it even comes close to the sims are the two easiest of the entire tier seems... unwise.

I was advising him to upgrade to 4pc T13 though. ._.

Edit: Oh I see what you mean. If you're comparing the bonuses on a Patchwerk fight, yeah 4pc T12 bonus > 4pc T13 bonus. The 4pc T13 bonus is lackluster, you can't argue against that. The numbers have been run, and it doesn't equate to much more than a 2% DPS increase. While multi-dotting, you'll proc Shooting Stars more, making the first part of the bonus wasted. However, casting more Starsurges from insta-procs will increase the 10% bonus part, so I'm unsure whether it's a net bonus or loss.

Your example with H-Spine isn't necessarily correct, either. While you do need to hold onto an eclipse for the tendon, having 4pc T12 would probably make it possible to get another eclipse cycle in, and would significantly boost your damage, rather than casting the wrong nuke which is a huge DPS loss. This can also be applied to any fight in this raid, except Blackhorn, as you most likely would not be able to make a full cycle before the drakes reappeared.

I do advise people to upgrade from 4pc T12 -> 4pc T13, whether or not they have any T12H pieces. WrathCalcs/Sims are great for fights that you don't need to gimp your rotation much (Morchok, Yor'sahj, Zon'ozz, Ultraxion, normal phases of Hagara, P2 of Blackhorn), so the numbers wont lie during these parts. General tweaking can be made for the other fights, like holding onto eclipses or even sitting in them, but these are only temporary phases of the fight, and you're hampering your DPS if you continue to follow those strategies during a "normal rotation" phase.

tl;dr: I'm arguing your point without advocating 4pc T12.