I’m not very fond of Rogue Stars either. Played it a few times, but seemed too clunky. Far too many markers and status chits for our tastes.
However, Nordic Weasel does have Renegade Scout, which is a retro clone of Rogue Trader. More modern and cleaner rules, but still tries to capture all fun feel of Rogue Trader. It’s not exactly Necromunda, but the rules will enable you to get close to that kind of game. Lots of great expansions too.