"I also find it odd that the 125 grain 357 magnum load that earned the reputation was a semi-jacketed bullet. But Most of the 357 sig rounds I find have little or no exposed lead."
Not really odd at all, as the amount of exposed lead really has little to do with it anymore.
The Remington bullet that made the 125-gr.'s reputation was a "Generation 0" bullet, designed in the early 1970s (or earlier) when it was anyone's best guess what jacket, lead, form, and velocity would work well in a given handgun.
It wasn't until post Miami (1986) that manufacturers really started working on bullet designs in a scientific manner, aided with FBI's newly developed penetration and expansion criteria, to design bullets that would actually expand and penetrate consistently.
Those bullets, like the Golden Saber and the Black Talon, were Generation 1 bullets.
The .357 Sig's bullets took advantage of those advances in design to balance bullet design against expected velocity.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.