So my HD750 came in the other day, and I finally got a chance to fiddle with it Monday night.
It took some tweaking, and some experimenting, but I found a sound that I'm really happy with. It wasn't quite loud enough running at 8ohms through a 1x15 cab, but very close. I can imagine what it'll do with my 4ohm Schroeder 412...
There's some stuff in there that I'll likely never use, but the models I do/will use sound pretty good to my ears. I could easily do without the synth bass, as well as most of the onboard FX, but for the price it's a good solid head that I can see myself holding on to for a while (which is really saying something for me!)
All in all, based on just a few hours noodling time, I'd give it a solid 9 of 10.

Lighter would be better, but that's going to drive up price.
As a side question - any plans of making a LowDown preamp? Basically a stripped-down version of the POD series, with just the amp models and such of the LowDown series?