Re: the stable neck to rule them all
Multilayer laminated necks are very stable, but the downside is loss of liveliness and possibly tone too. Stiffness and hard sound is why I mostly haven't liked guitars made that way, especially neck-through axes using multiple layers of hardwoods.
no offence, but how many lam necks have you tried or actually built? I've made over 80 laminated necks and my guitars are never described as having a lack of tone. I've gone so far as installing a single piece neck on a guitar and later swapping it for a laminated neck. Same materials, just a 3 piece versus 1 piece. Just more stable. The reason for a 'flat' sounding guitar, lack of liveliness and so forth, is often the result of poor timber choice, poor pickup choice, poor hardware choice and a finish that's WAY too thick.
That being said: from experience, from building A LOT of necks: roasted maple is more stable than not roasted, but not MUCH more stable than a laminated one.
IMHO the best option for a superstable neck is roasted maple, 3 pieces, with carbon fiber stiffening rods, dual action truss rod as well as walnut pinstripes due to their longitudinal grain.
Oh, and for those who would scream my ears off saying 'YOU COULDN'T POSSIBLY ADJUST THE TRUSSROD ON A NECK LIKE THAT': sorry. no. I've recently made two 17 ply necks with carbon fiber rods and a dual action truss rod: stable as hell, but still really well adjustable.
Build a few, then judge.