I really don't think the students with the most talent always get the highest marks. Not at all.
That is because you can't quantify talent. It works the other way as well. Sometimes people get high marks while truly knowing nothing about the subject. I managed a 50 in Software Development while knowing shit all about coding. There were people in my class who got SS in the 30-40 range who have stacks more practical IT knowledge than I do.
I think it works the same in maths subjects too. Even though I'm far from good at maths, I didn't really think there was anything on the methods exam that was completely beyond my understanding. For the maths geniuses, the exams must really be a piece of cake which probably means the 45+ range is determined mostly by who made the most silly mistakes. I doubt there is much noticeable difference between ability once you reach that score range.
I have changed my stance on Further Maths. 50 is nigh impossible, unless you can go through a 40 and 60 mark exam without making one mistake, don't expect a perfect SS. Some years you may get lucky with difficult exams, which could mean you can drop 1-3 marks and still pull a 50, however I wouldn't count on it. If you are a good maths student and wan't to maximize your scores, then the methods/specialist path is the way to go.
A lot of people had the idea that if they were very good at maths, they could take FM for an easy 50. The problem is, the ease of getting a 50 is unrelated to subject difficulty. You still need to outperform the same percentage of people as any other subject so in actual fact, picking an "easy" subject like FM could have been detrimental to people who are good at maths because differentiating students at the high end most probably came down to luck with careless errors.
Also remember a lot of people had the same idea of trying to do FM after a more difficult maths subject like Methods or Spec. This meant that to score a 50, you would still need to outperform specialist level students.
it is incredibly difficult to get raw 50 in any subject
however, due to scaling, getting 50 is quite achievable with spesh maths, languages (in particular LATIN)
A little aside; according to the scaling report this year the mean scaled SS for Latin was a whopping 45, probably brought about by the fact that a 30 raw in Latin scales to that score anyway.