Is it possible that the stainless is carving through windings faster than nickel fretwire would?
Immortal frets still seem like a big plus.
My strings have always needed to be changed after a few hours use; I play hard and have very corrosive sweat. I can play six hours or a bit more on a set in rehearsal. But I could only ever get three hours stage time out of them, even when wiped down with FastFret after a set to inhibit corrosion. Have to keep track of the flight hours or they'll break. Not 'might break,' will break.
It was such a luxury traveling with a tech who'd take care of restringing, maintenance and tuneups!
Those days are long behind me now of course.