Are you sure you were using roaming data on the Refund plan? Under the terms of the refund plan, roaming data is consumed at 18 times the rate of non-roaming data, which makes it get used up terribly fast!
Your Moto X1 would have been using CDMA, and there’s a fairly significant difference in coverage between the two in your area. Requesting the CDMA SIM card would very likely provide you more access to data.
You mentioned using maps, twice. Did you know Google maps allows you to download maps while you’re on WiFi to use offline? This would allow you to have GPS without needing roaming data.