I'm Canadian, and when I roam to the US, I get AT&T in place for Rogers (some agreement or w/e). So I'm wondering, if I buy a Samsung Galaxy S4 (LTE; quad-core) locked to AT&T, would it work on Rogers without unlocking it first? And if I do need to unlock it, would the LTE still work with Rogers?

Otherwise, do you think I'd be better off with the octa-core version (no LTE)?