I do know from travelling in a dozen countries that the GSM systems work better than the CDMA etc in the US and Canada.

Canadian cellphone companies have changed to GSM, or are in the process of doing so.

I have had a Verizon phone in the US, and will never buy another one. I think tha the reluctance of several US vendors to use the international standard (GSM) is one reason for the poor penetration of cellphones in the US relative to many other countries. (Here in Norway there are 5 million cellphone lines and under 2 million landlines nowadays. Coverage is much more complete than in the US, despite very rugged terrain.)

Agreed that LTE is the future, but it will be several years before it has good coverage, particularly in the more remote sailing areas. We have LTE systems in a few Canadian cities, but no handsets for a month or so. In any event, all the LTE smartphone handsets for the next few years will probably have backwards capacity for GSM and GPRS

GSM is the only thing to buy for a sailor today, unless he is staying in the US, or other local are where CDMA is the only game in town. Even in the US, I think GSM is the best buy.