The III had too much cabinet resonance for my tastes (of which most owners of them either denied, did not notice or actually preferred). I have found getting honest, critical assessment of ANY Klipsch product futile here on the fanboi site. I would love to get a non-hyped, honest DETAILED comparison between the III and IV, other than "it's better". My hope is to one day get a Heritage design that has a completely sonically "invisible" cabinet. A Cornwall or La Scala that completely disappears like the best British monitors or electrostats would be what I am after. Right now the closest I can get is Forte I and it is not nearly close enough.
I would love to audition a AL5 or Cornwall IV in my home, but I would feel guilty returning them if I did not like them. Due to the shipping costs would be damaging to the store that allowed for this.