Phillips and Tipton are at different ends of the spectrum on this issue and thre is still much debate.
in the first paper, Tipton argues (IMO) solidly for an upper limit of 3.0 g/kg for strength athletes, about 1.4 g/lb. part of his basic argumen is that for healthy strength athletes
1. there may be benefits to this higher level that won't show up in short term studies. note that increases in muscle mass is only one of several places where protein is important and other pathways (such as immune function, connective tissue health) also reqruire protein; these processes may be upregulated by training but their requirements have not been measured.
2. there are no known negatives for the most part (and pre-existing kidney damage is a separate situation)
3. UNLESS excessive protein crowds out other nutrients. which generally won't be the case for an athlete meeting caloric requirements.
Basically, better to err on the side of slightly too much than slightly too little.
Phillips has always been at the lower end of the values.
I tend to side with Tipton, obviously.