We have a Garmin....several years old. Everyone we've talked to has had an occasion side-trip caused by the GPS. We just last night pulled in from a trip to FL and were still laughing at the point where ours told us "make a U turn!"....problem was we would have had to go over the concrete divider on I-75. Oops. Seems they all do this from time to time. But ours has been otherwise trouble free.
Highly agree that the larger size is better. Ours is maybe 3x5" at the most and would really be nice to have a quick glance at a larger screen. We're heading to CO later this summer and may look into a new one. Definitely the larger screen and definitely lifetime updates.