Grado doesn't go into a lot of details on the specs of their stylus tips. Ortofon specifies tip mass and also if it's nude or bonded.
The Sonota 1 was nude elliptical, the current Sonota isn't. I also heard from KAB and vinylengine forum that the 8mz stylus used to be nude but current production is not. So it would seem swapping in a current 8mz versus a gold stylus is maybe no longer much of an upgrade.
The cartridge is also a complete system, the more expensive ones from the older models may fit Prestige body but will likely work best In the older bodies.
Some people have better retipping outfits work on the Grado cartridges, which is another alternative to stylus swapping.