If **** hits the fan and I'm in spellweave, I merely press the spellweave button again and low and behold, 0.1 seconds later, I am just as mobile as you.
Well, as you said, the raids you typically attend are shattered/drunk, so it's no surprise that you are able to be so high on the parse without spellweaving. I prefer to just load up my "Tanks are crap" build, heavy into general for more hate decrease & then spellweave.
Most of the parses I see people post are meaningless, be one from "All Encounters", or a Guildstats parse on a fight where there is a lot of irrelevant AoE damage (i.e. Zodiac, Athyr Bast). Selective parsing through ACT paints a much clearer picture.