Affliction T10/T9 gear help

[Nibelung]

I'm currently running as an affliction warlock and i've recently bought head and shoulders for t10 warlock. However, i am not sure if i should break my t9 4 set which is just godly for affliction. My question is, when should i break the t9 4 set? (BTW i have drdamage addon and it states that my corruption and ua total dmg is higher when i have 4pc t9 then when i replace it with 2pc t10)

Another question is the T10 4 set which is: Each time your Immolate and Unstable Affliction spells deal periodic damage, you have a 15% chance to gain 10% damage done by you and your pet for 10 sec. Is this worth it for affliction? I'm not entirely sure if the 10% gain will affect the dots already applied and i would hate the fact of refreshing my dots based on the proc. does anyone have information/tests on how the 4 set works.

[SpookyGhost]

It's really frustrating, but you are going to be shackled to your t9 4-piece for a long time. I have two pieces of 264 gear sitting in the bank because replacing my 232 shoulders and 245 gloves tier pieces would be a DPS drop. The only thing I can say is that there has got to be a point when you replace enough t9 gear with 264 gear that it SHOULD, in theory, be able to replace the t9 4-piece set bonus, but I just don't know at what exact point that is. It certainly requires more than just two pieces of 264/two pieces of t10.

As for the t10 4-piece bonus I was wondering that myself. My guess is that you'd have to refresh your dots on the proc, as that's how those things generally work with spellpower, etc. But 10 seconds isn't that bad of a window, as you'd probably only really need to refresh UA/CoA anyway.