IS Boots’ top-selling Christmas hair tool really a cut above? Siobhan O’Connor compares the £39.99 Revlon volumiser with the feted £450 Dyson Airwrap and gives her verdict. It has also achieved more than 12,000 five-star reviews on Amazon. And a manager at Boots told me it is the store’s top-selling gift this year. So it has to be worth a try, right? FIRST IMPRESSIONS: The brush head is very...