Paul,

Actually it isn't the protein in a high protein diet that puts stress on the organs, it's the keytones. When your body doesn't have sufficient glucose for energy it will break down adipose tissue (fat) into keytones for energy and they are harder on the engine to run on so to speak.

"Ketogenic" diets are those that drastically reduce carbs in the system while increasing the percentage of dietary fats and proteins. If you made sure your body has enough carbs to process an increase of protein, you run just fine really.

Example: your macro nutrient breakdown was 40% protein, 30% fats, 30% carbs, your body would have plenty of carbs to process protein, and enough fat content for optimal hormone production.

Dr. Layne Norton, PhD out of the University of Illinois in Nutritional Science actually disagrees with the amount of protein your body can process at any one time too, which between 20-30gs has been the long standing rule of thumb.

Here's his paper on it in 2009 before he got his PhD.
http://www.abcbodybuilding.com/protein_size_&_frequency.pdf