The only "big" issue with pre-2015 Palazzo models are the Schwintek slides mechanisms. They have a very bad reputation for failure.
That one defect alone is causing significant numbers of owners to dump their recent purchases, (there are large numbers of late model gently used Palazzo's on the market).
In 2015 models a third rail,
(3TRAX), was added to help support the weight. I suppose if you can retrofit the new third rail mechanism, it might be a great buy, if the price is right.
Besides that, everything else is generally pretty good, being that it's the top of the line for Thor motor homes on a well tested chassis, with good systems.