Iron hands are definitely cool, but they also can get pretty.... intense. An individual iron hand can be a fun addition to a deathwatch team  to keep the tone grounded, but having everyone be brooding & embittered self-loathing hatemongers might get a little samey. 

if people are up for it though....

Raven guard are dope however. But so far it's three people who are at least ok with the idea of Salamanders