The Quicksilvers are often short on the list of amenities because they are designed on purpose to be lightweight. Check out the features before going too far on that. Otherwise, the handful of people I've run into who have them absolutely love them but I get the feeling they are more of a "tenter" mindset than other PUP owners. My impression is that they are tents inside a box with wheels on most of the smaller models. They do have some higher-end models with decent amenities but I think the price gets to be a little noticeable. The good news is that the wood won't rot out because they don't use any, at least in the core construction.
I have gone with used PUPs for both purchases and wouldn't want to be the one who pulls a new one off of the dealer's lot. I appreciate those who do, as it saves me a hit on the price and generally get the early quality problems sorted out. But I can appreciate the desire to have a year warranty and ownership of a brand new unit.
With that said, I was very picky about the condition of both and they came to me in near-showroom condition. The first one took me about 3-4 months of looking before I was satisfied. I probably looked at a dozen before I understood what people meant by "needs a little work" and such language. I would ask pointed questions before wasting their and my time with an onsite inspection. The second one was only a casual, nearly accidental find. Couldn't pass it up.
So if going used, look at the condition of the roof, the canvas/vinyl, the sub-flooring, appliances, etc. Look up under the hard roof on the inside of it to see any signs of water damage and rot. Look for bubbling in the ceiling covering inside (water intrusion).
Ask questions if there has ever been a problem (either while they owned it or before).
Have them (private seller or dealer) do a full run-though of all systems on the unit you're seriously interested in buying.