Birmingham do it on a wide scale now, and i've heard Leicester being the other one giving it a go. QMUL I think have tried it? again, in a narrower bunch, like Nottingham. Not sure how much they've expanded it this year.
If you're not intending to firm them then it's kind of pointless applying to somewhere you're not bothered about, because they may give an unconditional. I think it reverts to a conditional if it's insured, or rejected (?). If you haven't selected other universities yet then it's worth considering, but I wouldn't make it a deciding factor - because I doubt you're going to struggle with grades with a good background/predictions if realistic.