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I find that the worst co-conspirator with 7D noise is diffuse light, overcast skies, fog, haze, dust, etc. The cleaner the light and the sharper the shadows, the better off you are. While this is more or less true with any camera, I find it particularly true of the 7D and try not to have unrealistic expectations when the quality of the light is poor.
I find 7D doesn't like back light too much.
Overcast skies can easily fool meter into gross underexposure, which is why I usually add +1Ev to +2EV depending on how much sky there is in the scene. You can easily make an ISO 400 scene into an ISO 1600 if your not careful. Always check histogram.