I have had both side vertical stays break twice. Once sending it back to Mac to have removable stay tabs put in. I broke another and it was easy to just open the tube and put a new carbon shaft in but still, that is two failures. I have since put in my own carbon stays. The top horizonal stay has broken causing a tear/rip in the ribbon material. I have since re-sewn in my own horizonal stay and sewn a patch into the stay. It is more the stay problem than anything else. I have had one stitch problem, I take my pack off by the shoulder strap and a hand grab I had Mac put into my pack as I have bad shoulders and have to roll off my pack. One of the shoulder seams was ripping out and I had to put it on my machine and re-inforce it and the other side.
It might be the solution for most, it just my opinion it isn't bombproof. But then again, is there any bag or pack that is perfect for all users? I know I can't find it. I am actually thinking of buying a heavy duty sewing machine and making my perfect bag. I have just the one in my mind