Protein balance is one we discuss quite frequently. The quote from the Science Daily stating there's a need for larger, longer term clinical trials with older subjects on varied amounts of protein intake:

Note that the "varied amounts" is my adjustment to the proposed trial having subjects consuming from a range of low to high protein amounts. Yes, this is required to be able to really understand the dynamics of protein consumption as we age, and the cynic in me wonders if/when this will ever happen. My cynical self also suspects that "dietary experts" are still trying to find that "one optimized amount of protein for all" myth that likely doesn't exist other than very general guidelines tempered with caveats for many other variables in addition to age. This ultimately gets too hard to do and results in ineffective guidelines for all. Yeah, I'm really cynical about our ability to achieve this goal in today's chaotic nutritional climate.

I know from my own N=1 experiences, I can eat on the higher end of the Phinney/Volek recommendation for protein and do quite well. However, I also believe that negative impacts from too much protein (at least for me) could be mitigated by IF. My observations are that one of several reasons that periodic IF is healthy is due in large part to the absence of exogenous protein for periods of time. This enables the metabolism to clean out and re-balance. It may be in fact why I can eat more protein, very few carbs, and not have to resort to extensively increasing my fat consumption to achieve satiety when I'm not fasting.