the thing is that now it just doesn't work at all and there is no benifit so its not nerfed its broken, as in has no additive qualities to the gameplay. if fed isn't supposed to ever stealth then replace the ability if not fix it, probably one of the most useful leveling abilities hands down and no one can use it.
I used MES a ton on my escort in OB, and yes it needed to be toned down a bit. But they more then toned it down. It seems to work on npcs until you get within 8k or so. However in PVP it does absolutely nothing. I had klingons see me from 18k away while I was using MES and they were not even cloaked to get a perspective bonus. Another instance I was the only of 5 feds using MES, and the klingons came in cloaked and primaried me from 10k out.