for the mechanics, most RV's have 95% highway miles...not alot of starts and stops, cold starts etc.
so less wear on mechanics per mile than a car
more wear on suspension, many B's weigh 8000# +
as for lay out if you are tall likely better choice is a fore/aft sleeper, rather than side to side ( which also requires climbover to use the head)
watch out for "newer" battery and power technologies- older tech is proven- some of the alternatives have advertised more than reality
the advantages of the good newer tech will be available in a new build
watch videos online of how the sales people move about the RV as they display features- ease of movement says alot
we rented a B and learned much and then looked at 12 or 15 in person.
we are completely happy in our choice which at the time was 8 years old and 80,000 miles and cost 1/3 of new