I think I once played Gold with a lvl. 1 Ghost when I thought it was Silver. I was shocked to see the Crusader was even worse than I remembered so I went into the next game with a Katana to see if it would fair better. Then I noticed I had been playing Gold. Explained a few things.
Random Salarian soldier walks into Udina's office. Salarian: "I would like to know more about human culture". Udina: "We humans are..."
Depends on the class for me. With Adept I can do it easy at lv. 1. Biotic power + warp ammo + Wraith wrecks. Lv. 1 Ghost with a Harrier or PPR and one point in stimpack isn't hard either. I'll usually wait until lv. 8 for Engineers though, and wait 'til I can max out Charge + fitness and get 1000N on Charge on a Vanguard.
"Someone at BioWare ate lunch?! Must mean new Ham Sandwich faction!" -Bahslel, from Reddit