I was about to say the same as @Faultlinedid. We lobbied to have damage dealing IOs that did endmod to help out Elec Blast and Elec Melee sets.
The other endmod sets also enhance accuracy as there's no distinction being an EndMod Set or an Accurate EndMod Set which by design from the original dev team to allow spotting powers like Transference or Powersink that have accuracy rolls. Sure in Stamina you only need EndMod, which you can get via generic IO's+5 if you choose and then add a proc for maximized end gain in stamina, but your able to get pretty good EndMod with the existing sets in Stamina as is, especially since there is so much recovery bonuses and rarer end discount spread across a multitude of IOs.
Edit: I actually really like the procs for Synapse Shock, as I like to squeeze as much speed into my toons as possible when I reasonably can. Also the proc for Power Transfer is cool as well(just wish it healed for more, but beggars can't be choosers).