I've recently purchased a Dezl 770, rather preemptively . There are great reviews on YouTube, so I won't compete with that. I bot the Garmin vs the Rand McNally simply because I have a Garmin for my car and one of their handhelds as well and have great confidence in the product. Couple of things:

1. There are HOS features on the 770 but the 70/7 for Canada isn't an option, so related HOS features are useless in Canada.

2. Add to the price of a 770 the cost of a 32G micro SDHC card. You'll be needing one almost immediately after your first map upgrade.

Those are the downsides I've noticed so far, (besides the high price), but beyond that the 770 appears as though it will be every bit as functional and reliable as the other Garmin products I own.

Happy shopping all !