I live in a rural area, so lots of spotty cell service. Seems like I HAVE to keep Roaming Data turned on, which means I will burn through my data quickly
Please leave roaming data turned on. You are not charged for roaming data but it is used for texting and call setup. This was true for the Moto X on the refund plan too but a big difference here is that you could use chargeable data on the refund plan at 18 times the normal rate but their is no chargeable roaming data on the 3.0 plans at all.
simply put there is NO user Roaming Data on 3.0 plans (so there no need to turn it off and you will can not be charged extra) Republic app will have access to the little data they need to route calls and send texts
The easiest way to prevent your cell data use is to disable it in the RW app Cell data settings. Doing so will have no effect on your RW cell calls/text and you can enable it when needed. As previously said the Data and Data roaming should always be kept enabled in the regular phone Settings.