This upgrade definitely thematically and mechanically sets in stone what style of deck you're going to play, but I don't think I quite realized just how powerful this card is over it's predecessor until recently. The lvl 3 version forces you to discard if you end up with an ally under your control, while this version technically allows you to have allies under your control if they are cheated in with tech like A Chance Encounter and Flare. Allies are often some of the best cards in the game so it's worth considering. The only problem of course is this'll only work in multiplayer.
As an aside, any word on whether or not story allies can be taken? I think it's clear they can be put under your control during a scenario, but the modified deck-building restrictions seem to indicate that you cannot include story allies from scenario to scenario because they are usually described as "does not count towards that investigator's deck size" as is the case with Lita in Night of the Zealot. The key phrasing is "deck size" as opposed to "deck parameters" or something similar.