The Rogers Razr HD LTE has been out for about a week. It was Verizon that released their version yesterday. On the Rogers version, the bootloader is locked, but you can get an unlock code from Motorola on their website. According to Moto, unlocking the bootloader voids their warranty.
As for reasons not to buy one, I'd be concerned with the Dev support on the LTE (not Verizon's) version of the phone. I'm not sure that any US carrier is picking up the Razr HD LTE, so you may be stuck with Moto's software for a long time. Having said that, the LTE version has been rooted.