There is no logic in saying that the Asian 5 will get you a higher score. They aren't the highest scaling subjects and higher scaling won't neccesarily boost your mark.
^ five of the seven 99.95's from MGS this year did the Asian 5.
And the two that didn't are disqualified from Asian 5 only because they didn't do Physics.
the top achievers list from the archieve file that's available for download may also provide you with the source of that information
I think the conflict lies within being smart about making choices, as i said, if you really distaste a subject that scales up, don't do it. the premise of doing the asian five is that you don't have particular interests in any subject and is willing to work hard for a high enter. (for some subjects, like spesh, you may need to consider your maths average and put the effort in. this is why i suggest that you Think Twice about picking spesh, and other subjects likewise)
if you show a strong interest in a particular subject, i would say you will show a strong desire to study for it and thus achieve a high study score for it. why not give it a go?