Duke's personal stats are obviously boosted.
However, I will vouch that Obsidian's hours are gained through hard work and co-ordination.
They have been known to walk into bases and grab them with 3 guys, against like 7.
However...With that sten guy, it wasn't hacking.
It was most likely lag. You probably only saw one or two bullets fly, but in reality he was shooting off a whole lot more.
Also Staff don't transfer gang hours, and you cannot merge gangs by identifying. If you identify with two gangs, you end up owner of both. They don't merge.
TL;DR
Duke boosts. However, Obsidian's hours are legit.
Sten guy was most likely truly lagging.