I have the RV660LMT and so far it has been very good, where to mount it has been the greatest problem, it has virtually no battery storage power so must be connected to power while in use, maps and warnings are excellent, just make sure you input all your info and are in RV mode.
"Well that didn't go as expected"
2015 Chev 2500HD Highcountry Duramax
Cedar Creek Silverback 33IK
Donald&Casey cairn terrier
Rest in Peace Mary my darling wife.
Scottish by birth Canadian by time.