Just picked up our used 2011 23B last week.
The dealer offered a 48mo extended warranty, "PreseRVe Extended protection plan" for just under 2K.
Covers the following:
Chassis Frame & Hitch
Fresh Water System
Range & Oven
LP Gas System
Seals & Gaskets (? assuming you have to have the dealer do maint?)
Slide outs (mechanical & seals)
Now, as a general rule, I don't buy extended warranties. But I have been know to get them when they seemed reasonably priced otherwise worthwhile.
But we are new to this world, didn't have so much to worry about in a tent.
So I thought I'd see what the veterans here thought...