<p>I have no idea how much weight subject tests is in the grand scheme of things. But before I wrote mine I just told myself to try my hardest and if I score bad don't bother submitting the scores, but if I do well I dish them my scores. My feeling is that most people approach the tests this way.</p>
<p>You only don't need to submit GRE math subject scores if you're planning on going into AIM (Applied & Interdisciplinary Mathematics). I don't see how they could possibly hold it against you, since they go out of their way to mention at least 3 times on the admissions page that GREs are not required for the AIM program. My guess is they're trying to attract people whose background and expertise is more in a specific field (biology, physics, chemistry, etc) that the mathematical methods will be applied to, rather than the mathematical methods themselves.</p>
<p>I think it also depends largely on your background and transcripts. If you have all the appropriate coursework and did well in it, I think the exam is more optional. If you are missing a lot of the elective type courses that would help show your proficiency you might want to take it, especially, as has been discussed, if you are coming from a totally different background/major all together.</p>
<p>I mean, if you already have a masters in the field, the subject GRE becomes extremely optional in my opinion.</p>