So apparently on the PTR there has been a change to Lifetap, and not for the better. Instead of converting a base amount of HP into a base amount of mana and it scaling with spelldmg, it will now simply convert 16% of your health into 16% of your mana.
What does this mean? It means Int is going to be a much more attractive stat, and gaining more Stamina is actually going to increase the amount of health you sacrifice with Lifetap without actually increasing the mana you get back. This I find to be quite counterintuitive. Shouldn't getting better gear be a good thing?
Either way, this nerf was aimed at the arenas for sure where SL/SL Warlocks stack large amounts of Stam and very little int, so they'll be converting a *lot* of health into minimal mana = major nerf. The impact won't be quite so severe in raiding as HP/mana ratios are much closer to 1:1, but it will still be a nerf. Even less of a nerf for Affliction as Dark Pact is unaffected by this change.
What I *am* concerned with, however, is that this change combined with the Emberstorm buff is that Destruction Warlocks will be moving over to Incinerate as it will be casting faster and already was a better damage-per-mana spell(thus decreasing their mana consumption). That will mean Improved Shadowbolt won't be up any more and Affliction & Shadowpriests will suffer(Not that I'm surprised...)
On the optimistic side we may see some buffs come from this. Perhaps some PvP survivability changes against melee? Maybe increased DoT coefficients? I know for certain now that the devs knows the PvP issues Affliction/Destruction have and the raiding issues of Affliction. Who knows what's to come but I'm putting my money on some positive changes before we see 2.4 go live.