We have a Nexus Class C but for what it is worth there is no, zip, zero, nada, particleboard or plywood anywhere in our coach. Back in 2012 they were still subbing out the custom maple cabinets to local Amish carpenters and the quality shows.
The really cheaped out rigs out there have the contact paper stuck to particle board or plywood and of course it looks like {pick your metaphor here knowing that accuracy will get you banned}... When you find that level of garbage in any RV you can bet the rest of it was built about as cheaply as is humanly possible.
Quality, solid wood cabinets do not warp or crack and are usually fitted with equally well built hardware. That has been our experience after 6+ years and 60K miles.
:C