Role-playing remorse isn't "behaving for all intents and purposes exactly the same as a neutral". It's role-playing remorse, while the neutral or evil character wouldn't role-play remorese (and might actually role-play glee).

I honestly don't see why this is different than the situation for Marans. Maran's are all about destroying red-aura'd people, even if they're not doing anybody any harm. You could have an old, sick, paraplegic bed-ridden duergar, and if he had a red aura, Team Maran would destroy him in a heartbeat. And without remorse. Does that seem like the action/attitude of a "good" person to you?

The rubric I tried to use when interviewing potential marans was to see whether they really "got" that the whole "destroy evil" thing was only temporary, and was a means to an end (lack of evil and, hence, peace). I tried to make sure they were in it for the end instead of the means (i.e. doing lots of killing). Practically speaking, a Maran who was in it for the "means" would look about the same as a Maran who was in it for the "end", at least with regard to who they PK. The difference would be in how they role-play it with other people. Is that a "tangible" difference? I think so.