I agree that it's an individual level which is why I get concerned when I see things insinuating that nobody should go over 30 grams of protein per meal. Obviously that guideline can't apply to everyone.
It's a fine line between getting enough protein to keep your body from cannibalizing it's own muscle tissue to get the amino acids it needs and getting so much protein that you knock yourself out of ketosis although IMHO, it would take more than 30% of your calories from protein to do that. If it came down to chosing between slower weight loss due to excess protein and losing lean body mass due to insufficient protein, I'd probably go with erring on the high side.
I wish I had my Protein Power book handy as I think the Eades' address the issue of "how much protein is too much?" in their book, but it's currently on loan to my step-mom.