Well, I have had the '05D 39s for about 3 months. She was in the shop about half that time for a new roof and awning (caused be me and paid by insurance) and some body work (mostly caused by PO and paid by me).
Other than that I have been doing continual maintenance, pretty typical for a 10 yo RV. DW loves the space with the slides open, so floor plan is good for us.
Seems to be a reliable coach. Engine and transmission have been flawless. Fixed a couple of electrical issues, replaced bad GFI outlet, replaced house batteries, found bad fuse that fixed charging issue. Also removed old fashioned TVs. Replaced the front TV with a 43" visio (biggest one that would fit the space) and will replace the back with a 32". Thinking seriously about putting one outside in one of the bays.
Going to hit the road for three long trips this year. Will have freightliner go over the chassis systems once before we hit the road (air, hydraulics...). Other than that I think we are ready to go.
I would say the 2005 year is drastically different than the more current generation Discoveries. I went through a 2016 at an RV show recently and didn't even recognize it as a discovery.
2005 Discovery 39s Cat C7 330hp, AF1 brakes,
2013 Silverado Crew Cab Toad, Blue Ox Towbar