Questions about PvE affliction spec warlock Woltk

With my warlock I've gone with affliction and there are two talents Ive gone back in for in my head over putting points in and if they should be kept.

The first being improved life tap. The reason for this is that Im wondering if it would be smart to have better returns on this in terms of mana for big dungeons and bosses. I feel as though my sustain in terms of manna could be better. Then again I may just need to be better about using life tap on the regular in my rotation. I know Im not worried at all about the loss of life with this because of how quickly corruption will heal me back up along with drain life. So dont know if its worth talent point and is better spent towards something to boost my DoTs. Im somewhat leaning towards the latter option of not getting it but not sure

The second one Im actually more split than the one before which is improved drain soul. This one I know is also good for return on mana and arguably a lot more mana return at 15% at 2 points. That however isnt the main reason Im looking at putting points back in. I was more so thinking it would be good to have as a way of allowing me to do more damage and not have to worry about me pulling aggro from the tank. I obviously know I need to watch my aggro myself and lean off dealing damage when it gets higher but with this I wouldnt have to that as much so in a way it indirectly allows me to boost my dps by simply allowing me to do more without having to worry about aggro like I do without the 20% threat reduction.

So would love to hear your thoughts on both of these talents and also my thought process in considering them

EDIT: As I posted this and was looking at talents I realized I shouldve also asked about fel concentration because Im not sure I find it useful but I see so many people saying they find it as a must have. So wondering about that as well

Improved Life Tap is very useful. It means spending less gcd's getting mana, and more time doing damage. You'll be life tapping a good amount in any given fight, so this saves a pretty significant amount of time.

As for Improved Drain Soul, I think it's useless for dungeons and raiding. The mana return is something that can easily just be regained by life tapping after the pull, and the threat reduction isn't worth 2 points when you can just soul shatter. I view it as more of a leveling/questing talent.

If you take all of the damage talents (including Improved Life Tap), you should have 1 point remaining for Fel Concentration, Curse of Exhaustion, or Improved Drain Soul.

Fel Concentration isn't terribly important for raiding, but is a must have for questing or any situation where you are being directly attacked. Probably drop Improved Life Tap for this if any of these cases are true.

Curse of Exhaustion is nice, and probably better than 1/3 Fel Concentration if you're not going to commit 3 points. I generally take this for situational benefits on adds.

Improved Drain Soul I already went over.

Thanks really appreciate it . Improved life tap also makes a lot of sense to get as I think about it with me having a glyph oif life tap so Ill be wanting it to keep my SP up

After further discussion on the Warlock guides thread, I was convinced of the importance of Intensity (and to a lesser extent Fel Concentration) in the destruction tree. It's up to you what you wish to remove to get this, but maybe Improved CoA. Check out the discussion here: http://forum.warmane.com/showthread.php?t=312383&page=4

Any profession suggestions for afflic pve lock?