Spoilers ahead!

I'm having trouble deciding what to do about the Van Graffs and Alice of Crimson. At some point
early in my playthrough, I decided to turn them in with the NCR, giving them the evidence I found.
I promised Jackson not do anything about it myself, and that I would let the NCR handle them.
Felt like the best thing to do back then.

This was before I decided that I would go independent. I wasn't sure about NCR then, but now
I am positive that I will use Yes Man to push the NCR out of Vegas.

However, two things have been bothering me now;

1. I really feel like 'cancelling' them anyway, for what they tried to do to cass and have done to
other caravans. Though I gave Jackson my word, that's the only thing stopping me.

2. But... Will NCR still take care of them? Now that I have decided they will be moved out?

I would prefer to take out the trash, but I gave Jackson my word (which I really regret, now).
And I'm not sure what the effect will be if Alice and the Van Graffs are removed.

Any help/advice? Can anyone justify killing them for me (roleplaying-wise, I don't care about
extra perks) ?

Just kill them all, you even have to do so for a quest if you want to become a member of the BoS

Another reason for wiping them out is there tech weapons steal it all and sell to Mick&Ralph

If you kill the Van Graffs and McLafferty, Cass becomes stronger in combat (+15% damage with guns), and the NCR gets screwed in the long term (they lose their suppliers, although why the Van Graffs matter to the NCR is a mystery).

If you turn in the evidence, Cass becomes more durable (+50 life), and the NCR blackmails the Crimson Caravan and the Van Graffs into cooperating on favorable terms. You can still kill the Van Graffs later on; they will be hostile on sight.

Thanks for the info, but I'm already a member of the BoS and have no intention of bringing Cass inside the Silver Rush.
Also, I'm not interested in perks, I'm only interested in this roleplaying-wise. I don't really care about the NCR, as I'm
pushing them out anyway. But I promised them I wouldn't take matters into my own hands. I just can't think of a
good reason to break my promise and kill them anyway, story/roleplaying wise.

Edit: Interesting, I just read this at the wiki for the Van Graffs' quest:

As of Patch 1.2.0.31x completing Heartache by the Number peacefully will turn the Van Graffs permanently hostile.
Apparently, word gets around that the player turned them in to the NCR. This makes it impossible to complete both
Birds of a Feather and Heartache by the Number in the same playthrough.

How I wish this would happen for me... But I already completed Cass' quest long before applying any of the patches.
Game's fully patched now, but the Van Graffs are not hostile to me at all...