We do not have data on the 850GH. We carry the 8950GH, which is a little heavier than the 850GH and is a higher launch version of the 950GH. That being said, the FST 90 would be slightly softer in profile than the XP95, but not much and mainly in the tip section, based on our data. Both the XP95 and FST90 shafts are on the soft side of the average for all R flex steel shafts we have in our database.
Testing information I have seen is even closer than Rlafoone’s numbers and would make it, from a shaft profile standpoint, a very close match to the FST 90A, IMO.
I would expect the Nippon shaft to also be a better feeling shaft. They definitely have a different kind of steel shaft. I have built several sets with the Nippon Zelos line and my customers have been thrilled with their performance. Hope this helps! Michael