It's sometimes not clear whether to ask here or on main meta (an example Q: What about questions already answered elsewhere?). Advantage here is that the answer would be more specific to our site, and the advantage on main meta is that there's more eyes on the question. What criteria do you use?
Ask here if it only applies to this site; ask on the main meta if it applies to all the sites (or at least multiple sites). The question you linked to probably belongs on the main meta; I'll move it there
If in doubt, ask here.
Stack Exchange staff monitors all the Meta sites. Even if your question is intended for the developers, they should see it.
Questions that are specific to this site, such as discussing tags (discussion tags) or rendering bugs (bug design), must be on this meta.
If your question is applicable to the whole network, it would be a good idea to search the main Meta first; many ideas have been discussed there before. But this is not compulsory; it's fine if you want to be a member of this site and don't care that it's part of a wider network.
If you ask here and the question turns out to be applicable site-wide, a moderator may migrate it to the main Meta. This will be handled transparently: a link is kept here and will redirect you automatically.