it all depends how and how much you plan on using your phone when not on Wifi…we also have Xfinity Mobile and got back a couple of weeks ago after spending almost 3 weeks between SXM and SBH…for us, since we hardly use our phones when wifi is not available, Global Travel Pass wasn’t worth it…XM’s rates without GTP aren’t that much, so we just paid the $.20-$.40/minute for the very few calls we made w/o wifi…receiving texts is free, and only $.10 to send…we always have Data Roaming off, so don’t use any mobile data…for longer calls we used Wifi Calling…our total roaming cost for the trip was $6…but obviously ymmv