I bought the XT several weeks ago, and have used it several times so far. The display, is amazing, along with the amount of detail it is able to display. The upgrade from my Zumo 390 in processing power and internal memory is apparent, as when I go off route, the GPS doesn't take a minute or so to "recalculate", if you blink, you will miss it. The processing power is enough that there really isn't any wait time for any action you do.
I have put some of the satellite maps on it, and is nice, but obviously only so much detail due to screen size. Prior to my retirement, in the job I had, we used laptop size screens to display maps, and for several years, satellite maps on top of it. Like now, I find that the satellite maps are great to verify your position, what is around you, and what is ahead, but while moving, more of a distraction then a normal display. The Zumo does make it easy on the move to trigger between displaying the satellite maps or not.
About the only negative so far, other than learning the differences on how it handles routes and all the newer stuff from the older Zumo, is the sensitivity of the screen could be less. Not hard to get use to, but would be nicer if it was less, or adjustable.
On the forums, a lot of people are talking about the power output pins in the cradle being weak, and breaking. Garmin is replacing enough of them that the cables are now on backorder. Guess going cheaper on this is biting them on the hiney.