It won't hurt you to eat excess protein for a little while, but I wouldn't exceed 1.5g/kg unless you're hurt really badly. They found no benefits to exceeding 1.2g/kg, I believe it was, in a study that was done. I believe it was published in ACSM journals.
Yes, it is a renal concern.
are you talking sedentary people only?
in strength trained individuals .86kg/kg showed a decrease in whole body protein synthesis and a negative nitrogen balance with 1.4g/kg showing the best results in regards to increases protein synthesis without excess amino acid oxidation.
In middle age men (55-57) the RDA .8g/kg over 14 weeks with no exercise mid-thigh muscle area decreased by an average of 1.7 cm. The authors concluded that the RDA recommendation may not meet the metabolic or physiological all older people. Let me know if you want links to the studies.
Of course, this is a longterm thing.
That's where it is a grey area. As far as I know no adverse effects (as high as 2.8g/kg) have been seen in people with healthy kidney function. And that's up to 6 months. I would love to see more long term data, if you are aware of any more current studies on protein safety I would love to see them.

The point I am trying to make here is that for ageing people, active people (not only training), and people in a caloric deficit I feel the RDA .8g/kg is too low. Especially for people like vegetarians for example, who find it harder to find complete proteins reaching that amount may be flirting with low protein levels. In regards to maintaining or adding LBM with no adverse effects seen in a huge range above but negative effects seen close too .8g/kg or lower why would you not consume more protein? And I am not advocating cutting out one macro-nutrient but setting your protein and fat and protein requirements and getting the rest through CHO based on your target calories.
And I still have to disagree, a high fat meal like cheeseburger and small fry should at least satisfy you. If it doesn't, then that is odd. You don't need to feel full to feel satisfied. Of course that's a mentality thing.


Small portions ONLY apply to energy dense foods.
You can have very large portions of high nutrient dense low energy dense foods and be fine, of course. It's much better to eat a large bowl of salad with chicken breast and tomatoes and peppers for example, than to eat 3 double cheeseburgers, but if you were to eat one double cheeseburger, it would be a better choice. However I'd rather eat a huge salad that one cheeseburger.
Ok, I am weird then . I think we agree here, I am not advocating going on a binge and think your advice about small portions works well but the amount of "junk" can be left to discretion with little to no effects within a realistic range if you know your daily caloric intake.
Have a happy Thanksgiving!