I ran a Rogue Trader short scenario/demo at DunDraCon over the weekend to a table of 8 and 2 folks that just wanted to watch even though there was no more space.
The scenario was fairly simple: a relative of the RT arrives on a lighter while the vessel is still some distance out on it's approach to Port Wander . Hyjinx ensue on the ship (no spoilers here ), culminating in a good starship battle.
The players really enjoyed the game, though there really wasn't enough time in the 4 hours to get too deep into a scenario.
The starship combat piece went particularly well, with everyone having something fun to do during the combat.
All in all, quite a fun little jaunt.