[quote=@Ellri]
Yes, it would be convenient to have the buttons be [quote], [@quote] & [@Mention] or somesuch.
[/quote]

There's an idea. Have the buttons be [[@][Quote]] [@Mention]. If you get what I mean, no padding between the [@] and [quote] so they appear to be two parts to a single button, making the [@] a mentionable quote.

It'd be no smaller than the rating buttons, so it's not exactly hard to hit. It preserves space. And being directly adjacent to the quote button, it makes it clear what it does. 

EDIT: Mockup, because I could:
[img]http://i.imgur.com/znKWy9j.png[/img]