The GPX files created by the Motion GPS are fine as of firmware 3084.
They use GPX 1.0 and include the correct header as shown in the example below:
<?xml version="1.0" encoding="UTF-8"?>
<gpx xmlns="http://www.topografix.com/GPX/1/0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
version="1.0"
creator="Motion-GPS"
xsi:schemaLocation="http://www.topografix.com/GPX/1/0 http://www.topografix.com/GPX/1/0/gpx.xsd">
<trk>
<name>/logs/2023/11/0610_2023-11-19-1429.oao</name>
<trkseg>
<trkpt lat="52.0493617" lon="-0.5709269">
<ele>43.195</ele>
<time>2023-11-19T13:29:57.000Z</time>
<course>319.456</course>
<speed>2.600</speed>
<sat>24</sat>
<hdop>0.60</hdop>
</trkpt>
</trkseg>
</trk>
</gpx>