I've done three 10 WS Gold games on X360.
Two were with my usual crew (Brannigan, ctc91, and Drake) -- it helps that ctc91 is really damn good at the game, so we could leave him to hold one flank while the rest of us murdered enemies on the other flank.
In neither case did we intentionally try for 10 WS. We just happened to have good combinations of characters -- I believe both were all Biotics teams -- so we killed fast.
We're also all veterans so we have all the usual veteran stuff: maxed manifests, know how to work the wave budgets, know where to shoot for double-hits on bosses, etc. etc. etc.
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The third 10 WS (actually my first, chronologically) was technically a PUG: me, Brannigan, Drake, and a random guy. Interestingly it was a mixed team, two tech and two biotics. I do know one of the characters has Inferno Grenades which are totally OP, so that helped.
Also this game was on Reactor (non-hazard) which strikes me as a pretty good map for getting 10 WS. There are lots of places you can stand that controls spawns and forces the enemies to funnel towards you so you can murder them easily. And, on the non-hazard mode, the objectives on Reactor are pretty tolerable -- even the 'inside the Reactor hack' isn't *too* terrible with a good team.
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I'd like to do 10 WS on Platinum some day, although I'd have to re-learn the X360 controller first. Too much time on PC lately. 