So A trap passing Umbreon is not a good lead but I sleep inducing Purugly is a good lead off
Yeah, trap-passing is largely considered to be somewhat dangerous within the current environment: Too many times, you won't be able to pull off a trap before the opponent crushes Umbreon.
This has been my problem with a lot of the "set up lead" type Pokemon that I've tried so far. Ninjask, while it does an excellent job (and the new X-scissor attack gives him far more aggressive viability), is largely sacrificing itself and all future viability in the match in order to swords dance once with Focus Sash, OR is engaged in a futile effort to pass one speed boost to something. In the case of the Dancer, it can have SOME level of viability, but if it has to switch, it will almost NEVER return in the match due to Sandstorm/Spike type things.
Umbreon suffers from largely the same problem: Yes, it trap passes... once. Essentially trading itself for one foe's Pokemon, if it's lucky and the opponent doesn't disable it. Those kinds of sacrificial risks are ineffective in an extremely aggressive environment, and largely suited for disabling a stalling/defensive environment... which I imagine COULD appear as a result of all the aggro currently around, but it's not particularly viable at this moment in time.
Status inducing leads on the other hand are exceptionally good: They disable opposing leads, and can wreck havoc if returned later to induce status during a stat-up attempt in preparation of a sweep. I'm having a lot of success with Jolteon (although you have to watch out for Electivire sweeping off a switch into Thunder Wave), and also mixed success with Milotic (as it can usually take a hit and Hypnosis/recover its way to victory).
Milotic might not actually be the best choice, but it's what I have trained right now. =P