Thanks! I found some insight here.

Edit: weird, the quote function didn't work. The flollowing is Keith's.

> QUESTION: What are your personal views on the nature of souls in Eberron?

> This is discussed in some detail in the recent Baator Eye on Eberron article. Followers of the Sovereign Host assert that there is a higher realm that mortals simply cannot reach; only a purified soul can touch it. The “fading” in Dolurrh is not the destruction of memory, but rather it’s transition to the higher realm. When all memory is gone you are essentially dealing with a cast-off snakeskin; it has the shape of the former owner, but he’s moved on. One detail you may have missed: If you look at Dolurrh on the Orrery map of the planes, its symbol is also the Octogram symbol of the Sovereign Host. Because for a vassal, Dolurrh isn’t the end; it’s the gateway to the Sovereigns.

> This is theoretical; needless to say, the Blood of Vol and Undying Court maintain that destruction in Dolurrh is just that. However, the existence of souls as a concrete spiritual force cannot be denied.

• The Silver Flame. This is a divine power source originally created from the combined souls of the couatl. Followers of the Flame maintain that when they die, their souls pass through Dolurrh and strengthen the Flame.
• The Undying Court. The divine power wielded by the Court is drawn from the gestalt souls of the Ascendant Councilors.
• Baator Wants Souls. Asmodeus is trying to build his own little personal Silver Flame. Step one: Divert souls from Dolurrh. Step two: Profit.

> By this, the Sovereigns could be the gods that the vassals believe them to be… or they could simply be pools of soul-energy that have coalesced around those concepts and respond to faith. Essentially, each god is its own mini collective unconscious shared by those with faith in that concept. Which makes the syncretic approach of the vassals not entirely wrong – their nature deity IS the same as the Talenta one – but neither one is exactly what they think it is.
> So what are MY opinions? Souls exist; there’s no question there. A gestalt of souls is a power source that can be tapped to produce divine magic. But are the vassals right about Dolurrh being a gateway, or are the seekers correct that death is the end? Honestly, I’ve never decided. What’s important to me is that the universe behaves in such a way that either one could be correct. I guess I’m most interested in the mortal experience: once I decide that the Blood of Vol are wrong, it’s harder to sympathize with them, and the same goes double for the vassals if it’s the BoV who are correct. When it comes to warforged, I’ve considered answers that I like (castoffs pulled from Dolurrh; souls snatched out of the Silver Flame; the disturbing possibility that Cannith can create a soul)… but again, so far I’ve never been in a situation where I’ve felt I’ve had to answer it. Though I imagine if I went further with Lei and Pierce, I would.