I think blaming the developers for high CPU usage is jumping the gun. The fault lies with the slow progress of consumer level CPU technology, not with people who actually want to do accurate emulations. There is a lot more to emulating tubes than a lot of the devs want you to think, and contrary to popular belief, something that barely touches your CPU isn't exactly going to be a component-level emulation of whatever unit it's claiming to be.
I haven't tried this out yet, but have heard good things. I heard some tests done on bass guitar and drumbus, but they sounded absolutely horrid. Not sure why - maybe user error.