I have always been a bit confused by the various options with Xert. A recent podcast helped me understand the remote player, however …
I am thinking of upgrading to a Garmin 530 to take advantage of the new data fields and be able to monitor MPA etc. Do you need to use your phone for that? If so that would require data to be enabled I assume. If so then is that a heavy user of data. I ask because I only have a 1Gb monthly plan for my phone as most of the time I am using wifi and I was wondering if Xert would use it up.
You’ll need to configure and update the fields - update before every ride - while you have a connection to your phone. As this can be done while (still) at home, you would not use data from your plan, because it can be done via WiFi.
During your activity, no connection is required, unless you want to take advantage of other possibilities the Edge offers, like weather forecasts, phone/message signalling or tracking (share your location with the home front).
The data usage of this functionality is (very) limited, but you may not want to use it anyway.