What about the LPX makes you prefer it over the RS? I keep reading that the stihl is superior due to thicker chrome, holds an edge better, etc, etc. Some prefer Oregon but no explanation why. I'm using 3/8 .050
It is cutting just a little smoother and faster. Regarding faster, the main reason likely is the thinner chrome, so you can get it a little sharper. In addition both LPX and LGX will cut a slightly narrower kerf than RS, at least in .058 and .050. The fact that LPX cuts smoother likely is related to raker design, as LGX is like RS in that regard.
In .325 LPX has longer cutters than RS as well, which makes it last longer. I don't understand why Stihl make them so short.
This is my theory/observations, I may well have missed something - but anyway it is the cutting that counts, and it leaves no doubt, even though the differenses are small.