I assume that the Razr HD will work the same as the Razr's regarding using it with a foreign sim. When the Razr's got ICS, their global radios were unleashed becoming true global phones. At that time, if you were to ask Verizon, you were told that it was locked and could only use Verizon international data (they do not want you to think any differently because they would like your money). But if you asked Motorola, they let you know that you could use a foreign sim. The latter proved to be true. See
International travel with Razr Maxx
My Razr M has the same gsm global radios that my Razr Maxx has, so I assume it will be able to use a foreign sim just as the Maxx is and that it will be the same for the HD's.