Will slaughtering The Dozens come back to haunt me?

[DafyddRW]

I'm playing through Pillars of Eternity for the first time (a little late to the party but alas I'm enjoying it) and I want to make sure I'm not making a game-ruining mistake here. I've decided that I'm going to side with the Crucible Knights this time through so while I was progressing "Rogue Knight" I traded Penhelm his Affidavit in return for Osric's Breastplate, only to discover that this version gives me the Quest Item Breastplate and not the equipable version. I then went to talk to Osric but there was no option for me to keep the Breastplate for myself so it seems like the only way to keep the Plate and keep Penhelm alive is to kill Osric and fail the quest. I saved and tested this, and I did get the equipable variant of the Plate but turned the entire Dozens faction hostile which led me to slaughter them all (gaining Cloudpiercer in the process) and before progressing even further I just want to make sure that this won't completely screw me over later if I wasn't planning on siding with them anyway.

 

(Off-topic; after getting hooked on PoE I wanted to create an account for these forums only to realise that I'd actually created one back in 2013 and had completely forgotten about it. So this isn't technically my first post, but I'd consider it to be.)

[FlintlockJazz]

There may be a quest later that requires you to get the location of a certain place from the Dozens, but as long as you don't mind slaughtering your way through them to get it from the box then its not a problem.  Other than possible loss of reputation for killing people I don't know of any other repercussions, not done it myself though so I cannot confirm.