Looke to me like it should, and I have a Nelf Mage so I can test if needed. It doesn’t seem terribly important, though. Do you have something specific in mind?
Im just the type of player whos race has to perfectly fit his class, when a racial has no use on a class I dont play that race, its kind of stupid but its just how my brain thinks i guess. If you could test if it increased speed for greater invisibility I would very much appreciate it.
Using TomTom, I set a point on the Path of Bones in Hellfire 73.50 48.50 and started from the spike on a post at 76.88 48.60, TomTom measures the distance as 174 yards. With very minor differences no doubt related to my quickness in starting, my Night Elf Mage, in Arcane spec, runs that in 20 seconds every time.
5% is not a lot, but it would make 1 sec difference in time or ~8 yards difference in length if Elusiveness kicked in, which should be measurable.
With Greater Invis, I do not see an Elusiveness buff while running, and I do not seem to reach the waypoint a second earlier. I arrive at the target point exactly as Greater Invis wears off - 20 sec.