Undead in DOS2 behaved in the same way. And like DOS2, undead in Pathfinder are healed by a different way, negative energy spells and effects. Seemingly why the game provides a lot of inflict wounds scrolls, or at least I'd think that's why. But it really sucks if you have party members like Seelah using Channel Positive Energy healing effects without the Selective Channel feat.
Life-Dominant Soul worked for that, I just expected it would solve the issue in general and being unable to use healing potions was really annoying.
You can use inflict wounds scrolls as potions ( I have like 50 of them in my Aion Playthrough), or make inflict wounds potions (You do not even have to learn to do that, your benched party members could do that for you in the camp). In Wotr you can even use potions in your party members (check the arrow over the potion) so other characters could also heal you.
I played a Dhampir in the beta, and I found it very useful. The enemy clerics/cultists and the Vermlek type of demons are adept at using channel negative energy against the party, and dhampirs are not only immune, are healed by it, so they do well tanking against that type of enemies. That also doubles against all types of negative energy attacks, like the vampire touch of the nabassus, etc
I didn´t find any enemy that attacks with positive energy, so the only problem is being damaged by your own party. You do not even have to make your clerics/oracles/pallys/etc learn selective channel, there is the feat you said: Life dominant soul. If you do not want to pick a feat, can also pick classes with the death domain ( inquisitors, clerics, divine hunters, druids, etc), at level 8 you are not damaged by positive magic.
That also works with the vampirism or lich curse of oracles and stigmatized witches
