but the internal speaker is not loud enough on a (my) motorcycle (ST1300 Pan European, so no loud pipes)
Also the XT lacks TPMS.
I'm not sure I like the XT user interface better than the 595, although at some points it's better. The xt is more square, and more screen estate is wasted (ie trip data column should be smaller imho) and you have to touch the screen about 8 times if you want to adjust the brightness from the map screen.
That being said, the screen is very very good, not only GPS but also Galileo (maybe Glonass), (re)start a trip from the 'closest entry point', quicker processor, better battery, topo and birds eye, wifi for updates, gpx-trasfer from you smartphone etc etc.
so imo the XT wins hands down