Have you considered a Hex-Beam? I know it wouldn't help on 40 and 80 meters, but every time I hear someone using one, they have a great signal and audio. I think they will handle 1500 watts, too. I hear a lot of DX happening on 17 and 15 meters, when I sit down at the radio with my morning cup of coffee. A couple of those guys are using Hex-Beams, and they always seem to be having QSOs with DX stations, that I can't even hear.
BTW, I've had great luck on 12 meters. I'm sure you have heard me griping about not being able to hear Europe with my attic dipole, but in the past couple of weeks, I've made contacts with Spain, Portugal, Wales, Denmark, the Isle of Man, and this just morning, Belgium. All SSB, and all on 12 meters. And I've heard several other DX stations on 12 meters, but couldn't break through the pile up. I'm really starting to like it.