An update on the dezl 560. I succeeded in getting my first map update. Pretty easy, but takes a while (lots of data), as in close to two hours.
If you go onto a road it doesn't have data about, it warns it may not be suitable for trucks (RVs), via a ding and an icon -- push the icon and get a text warning screen. Similar deal for steep grades ahead -- text includes grade percentage, but I have seen at least one road (not a major highway) where data was lacking, and it didn't tell me about a 9% grade (ouch). This was Sand Draw Rd. off of U.S. 287 (missed a turn coming out of a rest area -- my fault). Lane assist works OK, where they have data, though I've not yet encountered really confusing locations for that to help. It will often just accept that I want to go a different way than programmed (especially after the first warning), instead of repeatedly doing the "do a U-turn," or turn right on "X" road, etc.
I did discover a slight problem related to searching: I entered "Grand Teton National Park" while going across southern Wyoming (while at a rest area). It took a bit to come up with a search result, and in the meantime I'd gotten on I-80 again. When it finally got the results displayed, as I was about to touch one of the choices, it went blank recalculating distances (well, not really blank, but...) and five minutes later it still didn't have updated results. A bit later, when I was stopped, the search took a little bit, but the recalculation wasn't involved, and I could select my destination choice.
All in all, the more I use it (especially for the RV), the more I like it. It's especially nice that, when I don't disconnect power but just turn it off for overnight/whatever, I don't have to go through all the greeting/startup/etc. screens after pushing the ON button -- instead, I just choose "Where To" or "Map." Nice!