Omni is not nearly as easy to come by in this game as detection is in sc2, if you have something stealth and cloaked and the acu isn't there it will never be seen. Which will make a widow mine like unit incredibly unfun to play against.
Fire beetle balance suggestion
@archsimkat just realized, the widow mine cloak is disabled when recharging in SC2.
You can ditch the stealth entirely reminding low ranked players to build scouts, and if you want you can pair them with deceivers.