Slane is not a good guy. He says explicitly he was in love with the Witch and for a small trifle she wielded a purging wand against him. He admits to being in a relationship with that vile necromancer. Kill him and loot. That is the reason you get 6k exp and better loot.
Have you met Radeka? If you dont go on full "This ***** is evil" alert the second she starts talking then youve really rolled a 1 in perception. Shes Black Ring aka the club of the cartoonishly evil weirdos who cant go two seconds without being creepy in some way.
It's a shame that killing him yields significantly better rewards than helping him. Would prefer not having to choose between levelling and gearing my characters or staying true to their personalities in a role-playing game.
It's a meaningful choice, you can choose the easy and ruthless way of seeing everything and everyone as xp, or move on without killing. You don't NEED every single xp point to clear the game.
I couldn't imagine striving to get every bit of rewards this game has to offer. It's not role playing, it's simply min maxing for the sake of being as leet as possibly can be attained for...fun?
Completing the quest gives you one of the worst rewards I've seen. I mean you save this big dragon from eternal torment and he gives you something you would loot on a simple magister. Also he's too full of himself, aggressive and doesn't help you at all. Kill it! Do it!
But by doing his quest you get the XP and loot from Radeka and her stooges. (You can get tormented souls from the bloody corpses.) And then you can just kill him anyway. Between the Helm of Braccus and the first purging wand you should have more than enough charges to not need his help with shriekers
