We see a lot of players in S flex at those weights, not as many R flex. Since flex is often determined (for the most part) by club head speed, if a player has a speed that indicates an R flex, generally we see better results with lighter shafts. That being said, if an R flex player likes the feel of the heavier shaft, the tour weight shaft, and the trajectory and distances are acceptable, then there is no reason why we would not fit them into an R flex in the 125+ weight range. Doesn’t happen that often anymore and the advantages of going lighter for R flex speed players usually outweigh going with the heavier options. Lighter options, if they ae OK with the feel, can provide them with a little more speed and be easier for them to swing. Again, very much a generalization and each case is different.
One thing to add, just because a player may have higher club head speed and could play a 125g+ shaft, does not automatically mean that is what feels best or works best for them. I have fit a lot of really good players in 115-120g premium steel shafts.
Britt Lindsey