The Impact advantage on the super speed powers can help a lot for damage builds. But there's some bugs there that can be interesting. I would post these to the devs but it would most likely be pointless.
Bug 1: You cannot use Sword Cyclone power with this advantage. The moment you turn on that power your Impact will toggle off. Even if you stop using the Sword Cyclone power the Impact advantage buff will not toggle back on until you stop your travel power and restart it.
Bug 2: Super Speed's version of Impact advantage works, but for some reason Mach Speed does not seem to. Every time I tried to use the Impact with Mach Speed it would never toggle on and the damage wouldn't be increased. Which is a shame since I actually prefer the Mach Speed animation over the Super Speed animation version.
Third issue is that some powers just won't register the bonus. This is possibly a bug but more likely working as intended since all of these powers have specifics to them which makes sense for ignoring the advantage.
There is a fourth issue with this power but it is not a bug: This issue is probably working as intended since the tooltip specifically states damage bonus not power bonus, regardless I should still mention that the bonus only applies to damage not to healing or shields or control powers. Or at least, it has not helped anything I have tested it on. Mentioning that just in case someone was unaware that the advantage is intended for damage bonus only.