I am currently on T Mobile in US. I travel frequently and use many different SIM cards (e.g. AT&T, T Mobile, Verizon, random overseas SIM Card). Is it advisable for me to get the Verizon fully paid version? Will it work for me with T Mobile and worldwide when I switch to other SIM cards? I tired asking Apple Support but they can't seem to give me an answer. They just told me to check http://www.apple.com/iphone/LTE/ which is not very helpful because apparently the CDMA+GSM doesn't list the countries I will visit (e.g. Singapore, Hong Kong, Canada) which are namely the GSM carriers. Also, are there any comparable differences in connectivity between the two models? I remember I read they use different antenna or of sorts? Help... anyone?