Being a stock maker I will take Walnut...Properly dried and cured European walnut is as stable as titanium..But factory wood is seldom cured and dried properly as that process takes too long and its too time consuming and expensive so in your case Laminate would probably be best or a good full length glass bed with I-beam aluminum stabilizers would work fine and give you the warmth and beauty of walnut..
Anytime you want to debate the finer points of drying veneer compared to drying boards, let me know, I've done both profesionally for 5 years.
you are correct in stating that properly cured and dried walnut is rare. I've never dried it, but Larch 2x4's take forever in a kiln and even then you leave the outsides overdry and the inside 9% moisture at least... Walnut is denser, it would suck worse. I would imagine that if you wanted to properly kiln dry walnut 2x8's you'd need to run about 150 degrees in your kiln for about 10 days. You'd want to pull all the wood out every other day and switch the bottoms with the tops too.
Now Larch veneer is a whole nuther animal, you could consider it a 'soft hardwood' or 'hard softwood' (provided you're not mixing dry logs with logs fresh off a truck, and your green end made an effort to vat soak the logs for the same amount of time) denser veneers always dry more consistantly, with less warpage and shrinkage. I don't care how long and how "carefully" a chuck of walnut is dried, it will NEVER be as stable as Birch plywood.
But then I only dried 250,000 3/8% veneer 6 days a week for 3 years
If you really want to start an argument you'd lose we'll talk about the structural advantages of 3/4" Fir plywood compared to 3/4" Fir boards of equal size. You can't make grain in a tree run 90 degrees perpendicular every other fraction of an inch...
