My preference for the XT, after much testing like yourself, is to use the Beta export but I only ever use shaping points and I use the Trip Planner exclusively.
I actually put at least 1 shaping point on every road on the route.
Yes it means extra work creating the route but for those times when I do go off route there are less chances for dodgy recalculations.
I did use the Track Visible option for a while but I have found it pointless due to the amount of shaping points I add.

For me Garmin Tracks have only one purpose.
UK Green Lanes (Byways Open to All Traffic).
I plot them on the OS Maps Software and Transfer directly to the XT.
No more accidentally going down a Bridleway and enduring the wrath of the Walkers and Horse Riders. 👍