Yeah, I was kinda trying to lob that softball to @Rigs, but since he considers it obvious he didn’t feel the need to address it so I’ll step in.
Minions or Heimdall HP boost will ONLY bypass max HP and be in any way different from a plain heal in the event that they fire before equivalent damage is taken. In the case of a 400-ish hp minion, that means that she must fire before allies are hit by ~2 slashes, a Telly plus a slash, a single Vela (+1-2 ticks of DoT), Drake, or Gravemaker (even if you cleanse the second tick of the burn). If you’re firing Slow heroes before essentially any enemy has fired, what is the likelihood that she is even relevant to the match at that point? Do you routinely lose matches with that strong of a start, necessitating foregoing a faster and more dependable hero for a hero who essentially holds advantage only on those types of boards?