Ok I spent over 4hrs today testing various things about dots and the change. I actually just read the post by the Dev acknowledging that things have changed. It was obvious for most of us that things had changed but I will just lay out by how much from my test/experiences.
Dot Resist (landing the spell) - After 1000 dot cast, and 1000 DD cast I can say with pretty much a 100% certainty that they have the exact same resist rate as DD spells. Now here is the part they are not telling you.... They seem to be acting as DD spells for the entire duration of the spell. Each tick representing it's own resist check, and the bad thing is spell penetration is NOT working after the dot lands. They are probably not coded to work well with dots because dots really didn't need much spell penetration.
So Spell Penetration helps in landing the spell but not dot resist ticks.
Dot Resist (dot damage ticks) - It seems that 60 resist is giving over a 25% resist rate now on dots. So if your dot does 1000 damage after damage gear (I am just using small numbers for simplicity), if the person you cast it on is wearing 60 resist they will resist about 25% of the damage from your dot. Putting it at around 750 total damage done. This wouldn't be to much of a problem is spell penetration was actually working with our dots but from the test I could run I didn't notice it helping on anything but the initial cast. 100 shadow resist put partical resist around 40%.
I switched into my nemesis set that I use to pvp with. It has a decent amount of shadow resist and with felguard I have around 90 shadow resist. I was resisting at least 40% of the damage from each dot spell that was on me. If I didn't out right resist a dot tick I would resist sometimes 200 or more of the damage. This is significant why???
Because Affliction suffers most from this. Demo locks have a naturally high resist rate, and Destruction Warlocks have nether protection + whatever resist gear they are wearing. I was talking to a few of the warlocks on my server and just talking to alot of the ones in various battlegrounds. Most of them had been rolling over affliction locks because they resist half the CC spells now. My one friend who is affliction said he respec'ed tonight because he can barely cast a CC spell now without CoS, so he took all his pts out of improving Corruption and CoA to free up pts to pick up Malediction, and Shadow Embrace, and toss the rest of the points into destruciton so that he can nuke.
For me, I just stopped wearing my spellstone. I found that I was never having to click it anymore other then the rare times I get silenced by a shadow priest or mage.
The resist rate that dots are seeing isn't really out of range in terms of what DD spells see. The problem is because a dot has so many ticks it gets 6 to 8 chances to experience these resist while DD spells are all or nothing for the most part.
With the increased resist rate and lower damage overall of dots, it doesn't seem like they are worth it anymore. It seems nuking is the best way to go because it allows you to use the resist curses to boost damage and lower resist, while doing the best damage possible.
Also all affliction spells seemed to have experienced this nerf not just dots. HoT, Fear, Spell Lock, Devour Magic, Seduction, Intercept, and Deathcoil all have this higher resist rate now
gg.
So what does all this mean? If you want to @*%! affliction locks, or if you play a class that is able to keep a lock from casting, all you need to do is wear around 60-70 shadow resist (which is easy to acheive with a few pieces of tier2), and you will never die to a round of dots again
gg.
I tried to figure out why more people are not seeing a big issue. I realize it's because so many people are wearing the pvp sets now which have no resist on them, and less and less people are wearing the raid sets in pvp. When I did respec afflicition to run some test with friends that are spec NP who wear nemesis, I wasn't able to kill them in 10 tries with a full round of dots. Between the resist rate now, NP, and trying to get 4 spells to land on them it's just not possible. A good destruction warlock should be able to kill a affliction lock now with no trouble at all if they know what they are doing.
Solution? Try to combine demo/destruction specs together and if you just can't live without corruption pick it up but I wouldn't go past the second tier in the affliction tree it's just not worth it. The particial resist make dots inefficient compared to DD spells now, and the damage they deal isn't remotely comparable, and it appears dots might get nerfed somemore since they devs feel they are still overpowered.