Actually I would like it if both choices, glyph and no glyph, were equal dps. This would mean that you could use the glyph for convenience and you could remove the glyph for fights were burst was needed/useful.
Spine, Magmaw and Alysrazor are fights in Cataclysm where this burst damage could be useful (because of extra damage taken).
Of course the glyph and no glyph could also tend to switch in power depending on encounter, uptime and other stuff.
But this concept would only be possible if: No glyph = glyph in terms of damage on a complete dummy fight.