What is the difference whether a putter is shortened from the tip or butt end?
Tip trimming will make the shaft stiffer than if you cut it from the butt end. The butt end of the shaft is the stiffest end so if you tip trim you leave more of the butt end which makes the shaft play stiffer. You cannot tip trim all putter shafts. There are many taper tip putter shafts that install into tapered hosel bores and if you tip trim this shaft it will not longer fit into the tapered hosel bore.