IMO, DIY rock just doesn't look as good as the real stuff. I always see home made rock and you can just tell that its man made. I hate when you can see human preference in aquascaping of real rock even. Its really distracting to me.
But if you do it, I would be interested to see how it turns out. It very well may be the future of SW, lots of places are limiting or banning the export of dry and live rock.