I picked the KG4s over Heresys 20 years ago. I now have both and have compared them at length. The reason that I picked the KG4s was that they sounded better to me at the time in the audio store (solid state amplification, probably poor placement of the Heresys).
I thought the Heresys were too bright and had poor base. I remember the SRV album that I used to compare them and I was blown away by the full sound of the KG4s, and while not as forward in the midrange, the bass and overall presentation was incredible for the price (which was about $200 less than the Heresys). I never regretted the decision, however, a few months afterward, the Forte came out and I wish I had waited for that speaker. It has the best of both the Heresy and the KG4.
Given the choice today (Heresy vs. KG4), I would buy Herseys, use tube amplification, and place in corners on 8" high stands.