if you choose to make Samson serve under Cullen's supervision Cullen will say "You saw something greater than yourself once, perhaps you can be made to remember that" in his typical Cullen manner.
but if you choose to exile him Cullen will say "It's too late for you to die like a templar, look into dying like a warden" and the tone it is said with implies raw hate. I think it's the single truly mean line Cullen has said the whole DAI. Cullen knows what withdrawal is like, so this implies great deal of hate. His hate for Samson was always there, but I feel that judging in this way you sort of bring his hate to the surface more and justify it.
In the first option you sort of give him a chance to try and see Samson in a different light, the second option is, imo, slippery slop for Cullen especially since he has made clear that he wants to leave hate behind and is not proud of himself for hating mages (and with mages things were much more personal)
If I remember correctly this is the only two options Cullen comments, he remains silent with everything else.
(this is what i meant, anyway, but I realize that perhaps I misunderstood what you were saying)