After playing in the Deathwatch demo last weekend, I was struck by how easy the mass combat rules were to play, and how they kept the focus on the players.
While Rogue Trader has two sets of mass combat rules, I'm thinking of using the DW horde rules for my campaign.
The RT Simple rules are very abstract, and don't allow the players to be involved in normal combat. I've used these, and had to add a trick or boss fight at the end to give the players a feeling that they were there. But there only so many times you can say "all your troops flee in terror and you are left standing there, face to face, with the Big Nasty."
The RT Complex rules are much more about running large numbers of small units around. They would put my non-wargamer players to sleep.
The DW Horde rules rocked in the demo. You got to pick up PDF hordes as allies, and could "spend" them to tie down one enemy horde. You could do that with your Rogue Trader troops. The horde vs. a single unit could do a bunch of damage, so I do worry about scaling it so as not to overwhelm RT characters, who are not Space Marines, but I think by keeping the magnitude of the horde down, it's doable.
I do have questions about using them with minis: How big is a horde? Do you get attack modifiers based on the size?
Looks like FFG is selling me a copy of DW, even if I'm running RT. Well played, FFG.