There aren't many 1700 MHz phones right now, but there will be in time. It wasn't all that long ago that 850 MHz GSM phones were pretty rare. I remember being excited to get my Nokia 6590i.
CA: SaskTel, Wind postpaid; Rogers, Bell postpaid iPad flex plans; US: T-Mobile postpaid data, prepaid voice; PureTalk (AT&T MVNO) prepaid voice/data; AT&T prepaid iPad plan
Hardware: Too much but notably iPhone 5, iPad Mini Retina LTE, Moto G LTE (N.A. version), iPhone 4. All unlocked.