The problem with voting on something like this is that most of us understand absolutely nothing about it. This effectively leaves the decision in the hands of the techno-nerds.
For those of us who stand outside of that elite crowd, we are most likely to ask 1) What does the result look like? and 2) How easy is it to use?
It seems from the meta article that some of these proposals may be easily learned, (but I can't be sure.) On the other hand, except for a couple of very short mathematical expressions, there are no examples of what these might look like, particularly for the hieroglyphics and musical material.
I fully recognize that several specialized subjects require specialized tools, and they should be available to those who want to write about such subjects. I hope that whatever is adopted will be adequately documented for the rest of us. Also a person who wants to enter music (for example) should not need to learn how to enter mathematical formulas.
I create a page to allow people to see syntax proposal with concrete examples:
http://meta.wikipedia.org/wiki/Extension_Syntax/Example
Please remember the vote is about finding syntax to encapsulate extensions, not to decide the syntax of the extensions themselves.
Aoineko