We purchased a new/unsold 2008 Endeavor 40PDQ in June of 2010. These coaches were built at the end of the Monaco ownership just before bankruptcy. It seems that they were put together in some cases with whatever was on hand and so not all are exactly the same,
For the first couple of years we experienced what I considered an unusual amount of weird problems but in researching on the web it looks like the standard for most in that era. We had the radiator blow our first trip out. The diesel tank developed a leak at the weld for the drain plug. The windshield wipers stripped the post during a rain storm. The radiator overflow tank split and had to be replaced.
One of my biggest gripes is that the PDQ model has the refrigerator in the slide and the extra weight on that corner broke the slide roller and tore up the bottom of the slide. The repair was to install new metal rollers and put stainless plates on the bottom of the slide.
Another weak point seems to be where the front cap attaches to the roof if it has leaked at all the screws holding it together will be rusted out. I put Eternabond on every joint on my roof as soon as I heard about this so not a problem for me.
Hopefully by looking at a used coach someone else has taken care of most of the problems for you.
We spend about 6-7 months a year on the road and love our coach now that the problems are behind us. Except for a door scissors arm replacement last week the last four years have been pretty much trouble free. Love our Cummins ISL 400, plenty of power and I average about 7.6 mpg towing a Ford Explorer.