We have a 33' 5er, but some of my experiences may be of some help to you.
#1 - Cedar Creek/Forest River warranty service can not be overstated. They made everything perfect and then some ( Great Service from Cedar Creek
One of the things we asked the factory to add when it was being repaired was a TrailAir pin box. I'm sure many others aren't bothered by it, but I find the natural up-and-down of a trailer caused me stress/concern which made me get tired (...irritable according to the DW...) after 6 hours or so. Now, I've gone 10+ hours before getting as tired.
Tanks - ours were mislabeled... Our dealer found out the hard way when he opened the 'gray' tank onto the ground at the shop....
Walkthrough - this was our first 5er (first camper too) so we let the dealer give us a whirlwind 2 hour tour. It wasn't enough. Like the others said, plan for more.
Pin Tripod - I weigh 200#'s (~90 kg) so my wife notices me walking around while she's on the bed. Some other kind campers with stabilizing systems let us walk around in their units. We found the leg stabilizing systems to be consistently superior to the tripods. The systems made in China (sold in Camping World and other such stores) seemed less robust so I ordered the SteadyFast system. You can find it at SteadyFast: 5th Wheel and RV Travel Trailer Stabilizer System
. It took me an afternoon to install it myself - taking it very slow and easy. It makes an amazing difference.
TT vs. 5er - I've only towed a TT a couple times. The biggest difference is the height and frontal area. Fuel consumption is strongly influenced by your speed and wind direction. Height - measure your unit so you know what you can go under.
I didn't see it mentioned here but one thing I would definitely check before pulling out is tire date and pressure. I've had 2 sets of tires go bad - the first required $3k+ of repairs; the second I caught before the tire blew out. Several tire dealers have confirmed that trailer tires have a shelf life of 3-5 years - whether they are ever installed or not. With my experience and in the heat of Texas, I now change them at 3 years. You will find it as a 4 digit number of each tire in the format WWYY - week manufactured and the year. "New Trailer" does NOT equal new tires - my brand new 2010 unit had tires manufactured in 2008. And keep them inflated properly; low pressure equals heats which equals delamination which equals a blown tire.
Having been to the factory and met the people building these units, they are diligent and caring people who want to provide you with a quality product that you will enjoy for many years. Like us, they are people and subject to missing something along the way - there is a whole lot to one of these units. No matter how thoroughly you go through a checklist and look at things during delivery, there are somethings you just won't find until you're out on the road. Try to take it in stride and work with your dealer when you get back. If it's something that needs to go back to the factory, have confidence that you will be well taken care of.