As said before, used or new is a personal decision.
For my $0.02, I invest in stocks, some bonds, CD's, precious metals, and quite a few mutual funds. I don't view an RV as an investment, although nothing wrong with looking at it that way.
So in my personal choice, the depreciation hit doesn't matter since I figure that's part of the cost of enjoying the RV: I've bought 3 new and will likely buy the next one new. Prefer not to follow someone else and like to have a warranty, however illusory the benefits of that may be.
When I (or particularly the DW) goes into a used unit and smell dog, cat, "old" or "musty"...there's just no way to calculate enough benefit to offset that visceral gut reaction against "used."