Ron, I'm pretty sure what is being referenced is the addition of the micro ridge stylus. The prior model--LP-S did not have that stylus configuration. As can be seen in the update you referenced, all of the current models are now using a micro-ridge. I think the prior shape was an elliptical.
The other change that was added to the LP-S from the LP was an increase in the amount of metal in the body...resulting in a heavier cartridge. The body shape, weight and size of the LPS-MR is the same as the LP-S, but a lot heavier than the older LP. Nonetheless, the design is now a little long in the tooth, which is why it wouldn't surprise me a bit if the new Zyx's with the CF cantilever will show it off. My local Lyra dealer ( who happens to also stock the Benz LPS-MR) tells me that the Etna and the new Etna SL are in a different league as well. As they should be at a much higher price point!
I am reading the press release differently. I think it indicates that the LP S-MR was one of the pre-existing models.