I had PSS shaft seals on my last boat which I fitted while she was still in the water, 15 years and 9,000 miles later, still perfect).
My current boat had a stuffing box & packing rings which the PO had just kept tightening if there was a drip instead of greasing and re-packing, result ! Grooves worn in the shaft which I was fortunate to turn end over end and refit.
I fitted a PSS seal, 4,000 miles later I've never had a problem.
I wouldn't fit anything else but that's my personal opinion based on my experience.