I'd say the Spawn path is more about him realising that treating others as equals and that trust is an option. I do like the two conversations you have with him after the aborted ritual. I am not fond of that you cannot return the sentiment and tell him how important he has been in your character's life, which would be needed to keep the conversation level. I realise this might be difficult for ordinary Tavs but for the Origins - Durge included - this should be doable. After all Astarion helps Durge through a very difficult night and when I play as Gale, I can quite literally tell Mystra that Gale defied her command because of his new lover. It would be an excellent moment to both make your chosen Origin feel relevant and to tell Astarion that he has been just as important for your character as your character has been for him.
My second critique about None-Ascension is, that it is a bit lame. All the suspense of the scene is carried by the dice roll, not by the scene itself or even by the line of argumentation, which could be interesting. Tav is also very distant in the scene - I guess it was written with a paladin in mind - there is no moment to show sympathy for Astarion's situation. Astarion is also still reasonably calm throughout the scene, which is odd when you compare it to how the scene is described later on in dialogue. In the dialogue it sounds as if you talked him down from the very turning point of the ritual, which he wasn't anywhere near at in the scene.
As I have written in the thread about fixing Astarion's "good" ending, I recently did the None-Ascension in Astarion's Origin and it felt amazing. In his Origin the point of no return is after Astarion carves the contract into Cazador's back, this allows for the cathartic moment of carving the runes to play out and puts the final decision at the real turning point, where a flick of the wrist and the choice of tool decides about how things continue.
I also liked how my chosen companion, Gale (obviously ^^; ) handled the situation. He first shows empathy with Astarion and helps him because of it, makes his moral objection know at the point of no return and after freeing the spawn reveals that even his moral objections were also steeped in care for Astarion. I wish Tav had a smidge of the emotional capacity Gale shows in the situation because in the Origin version it felt like someone was having my character's back, and that their bond only grew through the shared experience. The companion version of the scene is sadly lacking all of this.
The Spawn path also needs a friends version of the graveyard scene.
