I did, it's a lot of fun.
I was playing my feral druid Sanic
http://eu.battle.net/wow/fr/character/ysondre/Sanic/ trought lvl 60-99 mostly in bg's with cap speed.
I move at 275% in dash (seem to be capped), 215% in travel form and 205% in cat form.
I still use my speed set to this day on my feral i found it better to swap items than to get a mount.
You are trully fast with this, it's very hard to stop you, once lvl 100 the items stop scaling but i still manage to have arround 270k hp with my speed set, which makes it still viable for speed flag capping at max level.
The most fun was in the lvl 90-99 bracket for me as pop were constant and i was nearly unkillable, won almost 100% of ctfs
I takes me 30 sec to reach the flag from the doors opening and then 40 sec to get back (because of the flag speed limit of 200%)
Fun fact: taking the speed boots will actualy slow you down by capping your speed to 200% !