Have you seen the footage played in its native format on an HDTV? I don't know about the videomaker footage, but I just shot some stuff using a Letus Ultimate, at night, with wonderful rich grainless blacks. At least, that's how it looks on my LCD TV played through HDMI. Can't speak for how it'll look after Voltaic or FCP or some other conversion gets through with it, but it looks fantastic.
There will always be some grain in any video footage from any 1/3" camera. I'd put the noise level of the HMC150 squarely up against an EX1 any day. It doesn't look as noiseless as a $48,000 HPX3000, but then again neither does an EX1. But compared to an HD100, XHA1 or HVX200, it looks practically grainless. And certainly far less grainy than film.
Barry, I trust your assesment, which is why I think it's probably the transcoding of the avchd that is causing the macroblocking. I know"grain" noise, and that isn't what I'm talking about. It's a "pixelizing" in the sky part that I'm seeing. I guess this could be overcome right now by importing directly through hdmi, not a perfect workflow, as time consuming as capturing tape, but workable if the pixelizing is avoided.