I am going to be 60 in 2 months. I can't play with string that stiff. I play with something soft like Cyclone Tour or gut/poly hybrids strung with a nice soft slick round poly cross that holds tension really well.
I do think for the right player with the right strokes that can compress the ball the Kirschbaum strings discussed are great but not for me.
There is a kid I string for that is a snapper.... He snaps anything you put in his racquet in less than a week no mater how stiff, how thick, how expensive.
So I suggested trying a really good string that is cheap and ride this out until he outgrows it which he will.
I ordered Max Power, Max Power Rough, Pro Line II, Pro Line II rough, and we have access to Super Smash. I am going to have him play with these and see if one of these will work and once he decides on one we can order some reels and he can just snap string to his hearts content.
I think he will snap the rough strings even faster but if it is what he wants it is cheap so it really won't mater.